Methods and devices for endovascular ablation of a splanchnic nerve

ABSTRACT

Systems, devices, and methods for transvascular ablation of target tissue. The devices and methods may, in some examples, be used for splanchnic nerve ablation to increase splanchnic venous blood capacitance to treat at least one of heart failure and hypertension. For example, the devices disclosed herein may be advanced endovascularly to a target vessel in the region of a thoracic splanchnic nerve (TSN), such as a greater splanchnic nerve (GSN) or a TSN nerve root. Also disclosed are methods of treating heart failure, such as HFpEF, by endovascularly ablating a thoracic splanchnic nerve to increase venous capacitance and reduce pulmonary blood pressure.

INCORPORATION BY REFERENCE

This application is a continuation of U.S. application Ser. No.17/152,665 dated Jan. 19, 2021 which claims priority to U.S. ProvisionalApplication No. 62/962,627, filed Jan. 17, 2020 and U.S. ProvisionalApplication No. 63/086,516, filed Oct. 1, 2020, the disclosures of whichare incorporated by reference herein in their entireties for allpurposes.

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

This disclosure is related by subject matter to the disclosure in U.S.Provisional Application 62/864,093, filed Jun. 20, 2019, U.S.Provisional Application 62/881,251, filed Jul. 31, 2019, U.S.Provisional Application 62/962,627 filed Jan. 17, 2020, U.S. Pub. Nos.US2019/0175912, US2019/0183569, U.S. Pat. Nos. 10,376,308, 10,207,110,App. Nos. 16/510,503, 62/836,720, 62/837,090, 62/864,093,PCT/US2019/15400, PCT/US2020/038934, and PCT Pub. Nos. WO2018/023132,WO2019/118976, and WO/2020/257763, all of which are incorporated hereinby reference in their entirety for all purposes.

BACKGROUND

Heart failure (HF) is a medical condition that occurs when the heart isunable to pump sufficiently to sustain the organs of the body. Heartfailure is a serious condition and affects millions of patients in theUnited States and around the world.

One common measure of heart health is left ventricular ejection fraction(LVEF) or ejection fraction. By definition, the volume of blood within aventricle immediately before a contraction is known as the end-diastolicvolume (EDV). Likewise, the volume of blood left in a ventricle at theend of contraction is end-systolic volume (ESV). The difference betweenEDV and ESV is stroke volume (SV). SV describes the volume of bloodejected from the right and left ventricles with each heartbeat. Ejectionfraction (EF) is the fraction of the EDV that is ejected with each beat;that is, it is SV divided by EDV. Cardiac output (CO) is defined as thevolume of blood pumped per minute by each ventricle of the heart. CO isequal to SV times the heart rate (HR).

Cardiomyopathy, in which the heart muscle becomes weakened, stretched,or exhibits other structural problems, can be further categorized intosystolic and diastolic dysfunction based on ventricular ejectionfraction.

While a number of drug therapies successfully target systolicdysfunction and HFrEF, for the large group of patients with diastolicdysfunction and HFpEF no promising therapies have yet been identified.The clinical course for patients with both HFrEF and HFpEF issignificant for recurrent presentations of acute decompensated heartfailure (ADHF) with symptoms of dyspnea, decreased exercise capacity,peripheral edema, etc. Recurrent admissions for ADHF utilize a largepart of current health care resources and could continue to generateenormous costs.

While the pathophysiology of HF is becoming increasingly betterunderstood, modern medicine has, thus far, failed to develop newtherapies for chronic management of HF or recurrent ADHF episodes. Overthe past few decades, strategies of ADHF management and prevention haveand continue to focus on the classical paradigm that salt and fluidretention is the cause of intravascular fluid expansion and cardiacdecompensation.

Thus, there remains a need for improved therapies for heart failurepatients that are safe and effective, and devices and systems that areadapted and configured to perform those therapies.

SUMMARY OF THE DISCLOSURE

The disclosure is related to methods of, devices for, and approaches forablating a thoracic splanchnic nerve or a thoracic splanchnic nerveroot. The ablations can be performed to treat at least one ofhypertension and heart failure, but the general methods may also be usedfor other treatments as well. For example, the methods herein can beused in the treatment of pain, or even to generally benefit the subjectto reducing the amount of blood that is expelled from the splanchnic bedinto the central thoracic veins.

The treatments herein may be accomplished by increasing splanchniccapacitance. The therapies generally include ablating a patient'spreganglionic thoracic splanchnic nerve or thoracic splanchnic nerveroot to increase splanchnic capacitance, and thereby treat at least oneof hypertension and heart failure.

Methods herein describe ablating thoracic splanchnic nerves, such as agreater splanchnic nerve or greater splanchnic nerve roots. Whilemethods herein may provide specific examples of targeting greatersplanchnic nerve or greater splanchnic nerve roots, it may be possibleto alternatively, or in addition to, ablate other thoracic splanchnicnerves (e.g., lesser, least) to perform one or more treatments herein.

One aspect of the disclosure is a method of ablating tissue bypositioning a medical device intravascularly in the vicinity of targettissue, and using the medical device to ablate tissue and create alesion. One aspect of the disclosure a method of ablating tissue bypositioning a medical device intravascularly into one or more targetvessels, and using the medical device to ablate tissue and create alesion. The methods herein can thus be described as methods thatposition a medical device near target tissue to be ablated and/ormethods that position a medical device in one or more vessels, where thetarget tissue is relatively near to the target regions within the one ormore vessels. Any of the method steps herein (including, for examplewithout limitation, in the claims or the Description section) can beincorporated into any other method of use herein unless specificallyindicated to the contrary herein.

One aspect of the disclosure is a method of ablating a greatersplanchnic nerve or a greater splanchnic nerve root to increasesplanchnic venous blood capacitance and/or venous compliance, the methodincluding advancing a medical device into a first vessel, advancing themedical device at least partially into a second vessel, and deliveringablation energy from the medical device to create a lesion in tissuesurrounding the first vessel.

In some embodiments the first vessel is an azygos vein and the secondvessel is an intercostal vein. The intercostal vein may be one of thethree lowest intercostal veins. The intercostal vein may be a T9, T10,or T11 intercostal vein.

The methods may include positioning a distal end of an ablation elementin the second vessel and no more than 30 mm (e.g., 20 mm, 15 mm, 12 mm)from a junction between the first vessel and the second vessel whendelivering the energy from the ablation element.

The methods may include a proximal portion of an ablation element beingdisposed in the second vessel when delivering energy.

The methods may include aligning or positioning the ablation elementwith respect to a boney landmark, such as a costovertebral joint at thesame vertebral level at which the second vessel (e.g., intercostal vein)resides.

In some embodiments aligning or positioning the ablation element withrespect to a boney landmark, such as a costovertebral joint, includesviewing the boney landmark with medical imaging such as fluoroscopy.

In some embodiments viewing the boney landmark with medical imaging suchas fluoroscopy includes orienting the medical imaging perspective at ananterior oblique angle in a range of 25° to 65° from AP (e.g., in arange of 30° to 60°, in a range of 35° to 55°) toward the side of thepatient where the target nerve resides.

In some embodiments viewing the boney landmark with medical imaging suchas fluoroscopy includes orienting the medical imaging perspectiveapproximately perpendicular to a line between the patient's first vessel(e.g., azygos vein) and the boney landmark (e.g., costovertebral joint).

In some embodiments aligning the ablation element with respect to aboney landmark includes aligning a radiopaque marker positioned on thecatheter containing the ablation element with the boney landmark.

The method may include creating a lesion at a distance of 5 mm aroundthe ablation element. Creating a lesion may include ablating a portionof a thoracic splanchnic nerve or a thoracic splanchnic nerve root,e.g., a greater splanchnic nerve or GSN root. A lesion may be acontinuous lesion. The lesion may have a length from 5 mm to 25 mm, suchas 10 mm to 25 mm, such as 15 mm to 20 mm. A lesion may be acircumferential lesion all the way around the second vessel. The lesionmay, however, be less than circumferential all the way around the secondvessel, such as 225 degrees or less, 180 degrees or less, 135 degrees orless, 90 degrees or less, 45 degrees or less.

The methods may include positioning an entire ablation element in thesecond vessel, while the method can also include positioning less thanthe entire length of the ablation element in the second vessel.

The methods may include performing an ablation process from within morethan one target vessel, such as an intercostal vein or an azygos vein.The methods of ablation herein may also be performed in the secondvessel.

The methods may include performing an ablation confirmation test, suchas any of the tests herein. If desired or needed, an ablation elementmay be repositioned into a second target vessel, which may be an azygosvein or a different intercostal vein.

The methods can also include, prior to, during, and/or subsequent todelivering the ablation energy, delivering stimulation energy to firstand second stimulation electrodes carried by the medical device.Delivering stimulation energy may help determine if the ablation elementis in a target location within the intercostal vein, and/or if anablation procedure was effective.

One aspect of the disclosure is a method that includes delivering anablation catheter comprising an energy delivery element (or member)through a venous system of the patient, positioning the energy deliveryelement at least partially (optionally completely) inside a veinselected from T9, T10 and T11 intercostal veins, delivering ablationenergy from the energy delivery element to create a continuous lesionhaving a depth of at least 5 mm and a length from 10 to 25 mm. Thecontinuous lesion and its parameters can be formed by selecting orchoosing certain energy delivery parameters that will create the lesion.In some embodiments, the lesion can extend from an ostium of an azygosvein to up to 20 mm along the intercostal vein. Any of the other methodsteps herein that are described in the context of other methods can beperformed with this exemplary method.

In some alternative methods herein, a plurality of ablations (i.e., fromablation energy on to energy ablation off) can be performed within asingle target vessel (e.g., an intercostal vein) to create a totallesion made from two or more lesions made from the plurality ofablations. The total lesion made from the plurality of lesions can haveany of characteristics of the other lesions herein. For example, thetotal lesion can be continuous (made by the connection of a plurality oflesions created during different ablations), may be up to 20 mm long,can be circumferential (or not), etc. After a first ablation, theablation device can be moved within the same vessel and create a secondlesion, which may or may not overlap with a first lesion. This can berepeated as many times as desired. Any of the stimulation or testingsteps herein can be performed before, during, or after any ablationstep, even if a plurality of ablations are performed in a single vessel.

One aspect of the disclosure is a method of positioning an ablationcatheter in a T9, T10, or T11 intercostal vein in a position forablating a greater splanchnic nerve (GSN), the method including imaginga portion of a subject, the portion including at least one of a T9, T10,or T11 intercostal vein and a portion of the subject's spine;positioning a distal section of an ablation catheter in the T9, T10, orT11 intercostal vein; and positioning an ablation catheter radiopaquemarker at a location based on the position of the radiopaque markerrelative to an anatomical landmark, such as one or more of a portion ofthe spine, a rib, a costovertebral joint, an azygous vein, or an ostiumbetween the azygous vein and the T9, T10, or T11 intercostal vein. Themethod may further include delivering energy from an ablation catheterablation element to ablate tissue.

One aspect of the disclosure is a method that includes characterizing arelative position of a patient's azygos vein to determine if the azygosis centered or substantially centered, right-biased (to the patient'sright of center), or left-biased (to the patient's left of center). Thecharacterization step may occur while viewing a particular portion ofthe patient's anatomy, and from a particular viewpoint that allows thecharacterization to accurately take place. The method may furtherinclude positioning an ablation catheter based on the characterizationstep.

One aspect of this disclosure is a method of characterizing the positionof a human patient's azygos vein relative to a portion of the patient'sspine, comprising: imaging at least a portion of the patient's spine andvasculature, in particular the azygos vein and/or one or moreintercostal veins, using an imaging device, in particular using aradiographic imaging device with a radiopaque contrast agent injectedinto the patient's vasculature, or imaging at least one radiopaquedevice, positioned in the azygos vein and/or in one or more intercostalveins, relative to a portion of the spine, using an imaging device, inparticular using a radiographic imaging device, to thereby characterizethe position of the patient's azygos vein relative to a midline of thespine, the radiopaque device optionally comprising a radiopaque portionof a guidewire; and determining if the azygos vein is centered,left-biased or right biased with respect to the midline of the vertebrabased on one or more images generated by said imaging device. Thisaspect may further include a method of determining a proper positionwhere a catheter should be inserted in a vasculature of a human patient,in particular in order to allow ablating a greater splanchnic nerve orgreater splanchnic nerve roots, the method comprising determining whereto place an ablation element of a catheter for transvascular ablation,in particular any of the ablation catheters herein, based on saiddetermination of if the azygos vein is centered, left-biased or rightbiased with respect to the midline of the vertebra.

This aspect may further comprise determining where to place a radiopaquemarker carried by the distal section of an ablation catheter, optionallya proximal radiopaque marker positioned proximal to any ablation elementcarried by the same distal section, based on said determination of ifthe azygos vein is centered, left-biased or right biased with respect tothe midline of the vertebra.

One aspect of the disclosure is a method of determining properpositioning of a catheter inserted in a vasculature of a human patient,optionally of a catheter according to any of the claims or disclosureherein, wherein the catheter comprises an elongate shaft with a distalsection carrying one or more ablation elements and a proximal radiopaquemarker, with the distal section of the elongate shaft positioned in aT9, T10, or T11 intercostal vein; wherein the method comprises:determining if the azygos vein is centered, left-biased or right biasedwith respect to the midline of the vertebra, assessing the position ofthe proximal radiopaque marker relative to the midline of the vertebra,verifying if the catheter is properly positioned relative to a patient'sanatomical landmark, wherein verifying comprises: considering that thecatheter is properly positioned when one of the following circumstancestakes place: if the azygos vein is right-biased, the proximal radiopaquemarker is placed at the ostium of the intercostal vein, to the right ofmidline of the vertebra, if the azygos vein is centered or left-biased,the proximal radiopaque marker is aligned with the midline of thevertebra.

In any of the method aspects herein, the proximal radiopaque marker maybe carried by the distal section and may be positioned proximal to allthe ablation element(s). The proximal radiopaque marker may bepositioned directly proximal to the ablation element or directlyproximal to the most proximal of the ablation elements carried by thedistal section of the catheter.

In any of the method aspects herein, the catheter may comprise a distalradiopaque marker positioned distal to all the ablation element(s) andwherein the step of verifying also includes: assessing the position ofthe distal radiopaque marker relative to the patient's costovertebraljoint and/or rib, ascertaining that the distal radiopaque marker isspaced from the costovertebral joint and/or rib at least a prefixedthreshold distance. The distal radiopaque marker may be positioneddirectly distal to the ablation element, or directly distal to the mostdistal of the ablation elements carried by the distal region of thecatheter, and wherein ascertaining comprises ascertaining that thedistal radiopaque marker is at least 3 mm, preferably at least 5 mm, farfrom the costovertebral joint.

In any of the method aspects herein, verifying may comprise consideringthat the catheter is not properly positioned when none of the followingcircumstances takes place: if the azygos vein is right-biased, theproximal radiopaque marker is placed at the ostium of the intercostalvein, to the right of midline of the vertebra, if the azygos vein iscentered or left-biased, the proximal radiopaque marker is aligned withthe midline of the vertebra.

In any of the method aspects herein, if it has been verified that thecatheter is not properly positioned, the method may further includeadjusting the position of the catheter by aligning the proximalradiopaque marker on the ablation catheter with the respectiveanatomical landmark, and/or by further distancing the distal radiopaquemarker from the costovertebral joint.

In any of the method aspects herein, a step of determining if the azygosvein is centered, left-biased or right biased with respect to themidline of the vertebra may comprise: imaging at least a portion of thepatient's spine and vasculature, in particular the azygos vein and/orone or more intercostal veins, using an imaging device, in particularusing a radiographic imaging device with a radiopaque contrast agentinjected into the patient's vasculature, or imaging at least oneradiopaque device, positioned in the azygos vein and/or in one or moreintercostal veins, relative to a portion of the spine, using an imagingdevice, in particular using a radiographic imaging device, to therebycharacterize the position of the patient's azygos vein relative to amidline of the spine, the radiopaque device optionally comprising aradiopaque portion of a guidewire.

In any of the method aspects herein, a step of assessing the position ofthe proximal radiopaque marker relative to the midline of the vertebramay comprise imaging, using an imaging device, in particular using aradiographic imaging device, at least a portion of the cathetercomprising the proximal radiopaque marker.

In any of the method aspects herein, a step of assessing the position ofthe distal radiopaque marker relative to the costovertebral joint maycomprise imaging, using an imaging device, in particular using aradiographic imaging device, at least a portion of the cathetercomprising the distal radiopaque marker.

One aspect of the disclosure is a method of determining properpositioning of a catheter inserted in a vasculature of a human patient,optionally of a catheter according to any one of the claims ordisclosure herein, wherein the catheter comprises an elongate shaft witha distal section carrying one or more ablation elements and a distalradiopaque marker, with the distal section of the elongate shaftpositioned in a T9, T10, or T11 intercostal vein; wherein the methodcomprises: determining the position of the distal radiopaque markerrelative to the patient's costovertebral joint, verifying if thecatheter is properly positioned relative to a patient's anatomicallandmark, wherein verifying comprises: considering that the catheter isproperly positioned when the distal radiopaque marker is spaced from thecostovertebral joint at least a prefixed threshold distance. The distalradiopaque marker may be positioned directly distal to the ablationelement, or directly distal to the most distal of the ablation elementscarried by the distal section of the catheter, and wherein the prefixedthreshold distance is at least 3 mm, preferably at least 5 mm.

In this aspect, if it has been verified that the catheter is notproperly positioned, the method may further comprise adjusting theposition of the catheter by further distancing the distal radiopaquemarker from the costovertebral joint.

In this aspect, a step of determining the position of the distalradiopaque marker relative to the patient's costovertebral joint maycomprises imaging at least a portion of the patient's spine andvasculature, in particular the azygos vein and/or one or moreintercostal veins, using an imaging device, in particular using aradiographic imaging device with a radiopaque contrast agent injectedinto the patient's vasculature, or imaging at least one radiopaquedevice, positioned in the azygos vein and/or in one or more intercostalveins, relative to a portion of the spine, using an imaging device, inparticular using a radiographic imaging device, to thereby characterizethe position of the patient's azygos vein relative to a midline of thespine, the radiopaque device optionally comprising a radiopaque portionof a guidewire; and imaging, using an imaging device, in particularusing a radiographic imaging device, at least a portion of the cathetercomprising the distance radiopaque marker.

One aspect of the disclosure is an ablation catheter for transvascularablation of thoracic splanchnic nerves, particularly for ablating agreater splanchnic nerve or greater splanchnic nerve roots, comprising:an elongate shaft having a length such that a distal section of theelongate shaft can be positioned in a T9, T10, or T11 intercostal vein,proximal and distal electrically conductive flexible ablation elementscarried by the elongate shaft distal section, a length from a distal endof the distal ablation element to a proximal end of the proximalablation element being from 10 mm-25 mm.

In this aspect the distal section of the elongate shaft may have anouter diameter from 1.5 mm to 3 mm.

In this aspect an axial spacing may exist between the proximal anddistal ablation elements that is from 0.1 mm to 5 mm, such as 0.1 mm to3 mm, such as 0.1 mm to 2 mm, such as 5 mm to 1-mm.

In this aspect the distal and proximal ablation elements may beelectrodes.

In this aspect the distal and proximal ablation elements may each have alength, wherein the lengths are the same.

In this aspect the distal and proximal ablation elements may each have alength, wherein the lengths are not the same.

In this aspect the distal and proximal ablation elements may each have alength from 5 mm to 12 mm, such as from 6 mm to 10 mm, such as from 7 mmto 9 mm, such as any length in any of these ranges.

In this aspect the distal ablation element may have a helicalconfiguration and wherein the proximal ablation element may a helicalconfiguration. A helical configuration of the distal and proximalablation elements may the same. Helical configurations of the distal andproximal ablation elements have one or more different features, such asone or more of coil direction (e.g. left-handed vs right-handed), pitch,or thickness.

In this aspect the distal and proximal ablation elements may each havecurvilinear cross-sectional configurations.

In this aspect the distal and proximal ablation elements may each haverectilinear cross-sectional configurations.

In this aspect the distal and proximal ablation elements may be madefrom a superelastic material such as Nitinol.

In this aspect distal and proximal ablation elements may be sufficientlyflexible and sized to allow the distal section to be advanced from anazygos vein into one of a T9, T10, or T11 intercostal vein.

In this aspect the distal and proximal ablation elements may each beattached to the shaft at distal and proximal end regions, but not inbetween the distal and proximal end regions.

In this aspect the catheter may further comprise a radiopaque marker.The radiopaque marker may be disposed distal to a distal end of thedistal ablation element. The radiopaque marker may be 0 mm to 5 mmdistal to the distal end of the distal ablation element, optionally 0 mmto 3 mm, or 0 mm to 2 mm. The radiopaque marker may be disposed proximalto a proximal end of the proximal ablation element. The radiopaquemarker may be 0 mm to 5 mm proximal to the distal proximal of the distalablation element, optionally 0 mm to 3 mm, or 0 mm to 2 mm.

In this aspect the distal and proximal ablation elements are each notconfigured to deploy to a deployed configuration.

In this aspect the distal and proximal ablation elements each have anoperational configuration that is the same or substantially the same asa delivery configuration.

In this aspect the distal and proximal ablation elements each have anouter diameter in an operational state that is the same or substantiallythe same as an outer diameter in a delivery state.

In this aspect the distal and proximal ablation elements may each haveexpanded configurations different than delivery configurations.

In this aspect the catheter may further comprise a temperature sensorcarried by the shaft. The temperature sensor may be disposed at a distalend of the distal ablation element. The temperature sensor may bedisposed at a proximal end of the proximal ablation element. Thecatheter may comprise a second temperature sensor, the temperaturesensor disposed at a distal end of the distal ablation element, thesecond temperature sensor disposed at a proximal end of the proximalablation element.

In this aspect, the catheter may further comprise one or more irrigationports in fluid communication with an irrigation lumen that isconnectable to a fluid source at a proximal region of the ablationcatheter. One of the one or more irrigation ports may be axially inbetween the distal and proximal ablation electrodes. Optionally none ofthe one or more irrigation ports may be disposed radially under anablation element structure. One or more irrigation ports may be disposedbetween helical windings of the distal and proximal ablation electrodes.In a side view, an irrigation port may be disposed between everyadjacent pair of ablation element helical sections of the distalablation element and the proximal ablation element.

In this aspect the distal and proximal ablation elements may beelectrically configured to be independently energized in monopolar mode.

In this aspect the distal and proximal ablation elements may beelectrically configured to be energized in bipolar mode.

In this aspect the distal section may be no more than 7 cm from a distaltip of the ablation catheter.

In this aspect the distal and proximal ablation elements may be sizedand adapted to create a continuous ablation having a length in a rangeof 5 mm to 25 mm, such as 10 to 25 mm, such as 15 mm to 20 mm.

In this aspect the distal section may be adapted for flexibly traversinga bend from an azygos vein to a T9, T10 or T11 intercostal vein.

In this aspect the catheter may further comprise a guidewire lumenwithin the elongate shaft and having a distal port at a distal tip ofthe catheter.

In this aspect the distal and proximal ablation elements may eachcomprise one or more of an RF ablation electrode, a coiled wireelectrode, a laser cut RF electrode, a RF electrode printed withconductive ink, a RF electrode on an expandable balloon (e.g.,conductive ink, flexible circuits,), a conductive membrane RF electrode,a RF electrodes on an expandable cage or mesh, an ultrasound ablationtransducer, an electroporation electrodes, an cryoablation element, or avirtual RF electrode.

In this aspect the distal and proximal ablation elements may each beadapted and configured to deliver ablation energy circumferentially tocreate a circumferential lesion.

One aspect of the disclosure is an ablation catheter for transvascularablation of thoracic splanchnic nerves, particularly for ablating agreater splanchnic nerve or greater splanchnic nerve roots, comprising:an elongate shaft having a length such that a distal section of theelongate shaft can be positioned in a T9, T10, or T11 intercostal vein,and an electrically conductive flexible ablation element carried by theelongate shaft distal section, the ablation element having a length from10 mm-25 mm, and a radiopaque marker carried by the elongate shaft.

In this aspect the distal section of the elongate shaft may have anouter diameter from 1.5 mm to 3 mm.

In this aspect the radiopaque marker carried by the elongate shaft maybe disposed from 0 mm to 5 mm from an end of the ablation element, suchas from 0 to 4 mm, or from 0 to 3 mm, or 0 to 2 mm. The end may be adistal end of the ablation element. The end may be a distal end of adistal ablation electrode, and the ablation element may furthercomprising a proximal ablation electrode axially spaced from the distalablation electrode.

In this aspect the end may be a proximal end of the ablation element.

In this aspect the catheter may further comprise a second radiopaquemarker carried by the elongate shaft and disposed from 0 mm to 5 mm(e.g., 0 to 4 mm, 0 to 3 mm, or 0-2 mm from a second end of the ablationelement).

In this aspect the ablation element may comprise distal and proximalablation electrodes. The radiopaque marker may be distal to the distalablation electrode, wherein catheter may include a second markerproximal to the proximal ablation electrode.

In this aspect, the radiopaque marker may be disposed from 0 mm to 3 mmfrom the end of the ablation element, optionally 1 mm.

In this aspect, the ablation element may comprise a distal ablationelectrode axially spaced from a proximal ablation electrode. The distaland proximal ablation electrodes may each have a length, wherein thelengths are the same or wherein the lengths that are not the same. Thedistal and proximal ablation electrodes may each have a length from 5 mmto 12 mm. The distal and proximal ablation electrodes may be axiallyspaced from 0.1 mm to 5 mm apart, such as from 0.1 mm to 3 mm apart,optionally from 0.5 mm to 1 mm apart. Distal and proximal ablationelements in this aspect may be any of the distal and proximal ablationelements herein, such as coiled elements. In this aspect across-sectional outer profile of a distal ablation electrode may bedifferent than a cross-sectional outer profile of a proximal ablationelectrode. Distal and proximal ablation electrodes may be made from asuperelastic material such as nitinol. Distal and proximal ablationelectrodes may be sufficiently flexible to allow the distal region to beadvanced from an azygos vein into one of a T9, T10, or T11 intercostalvein.

In this aspect, the ablation element may not be configured to deploy toa deployed configuration.

In this aspect, the ablation element may have an operationalconfiguration that is the same or substantially the same as a deliveryconfiguration.

In this aspect, the distal section may have a linear at-restconfiguration.

In this aspect, the ablation element may have an outer diameter in anoperational state that is the same or substantially the same as an outerdiameter in a delivery state.

In this aspect the catheter may further comprise one or more temperaturesensors carried by the shaft. A temperature sensor may be disposed at adistal end of the ablation element. A temperature sensor may be disposedat a proximal end of the ablation element. The catheter may furthercomprise a second temperature sensor, the temperature sensor may bedisposed at or near a distal end of the ablation element, the secondtemperature sensor may be disposed at or near a proximal end of theablation element.

In this aspect the catheter may comprise one or more irrigation ports influid communication with an irrigation lumen that is connectable to afluid source at a proximal region of the ablation catheter, includingany of the one more irrigation ports herein. One of the one or moreirrigation ports may be axially in between the distal and proximalablation electrodes. Optionally none of the one or more irrigation portsmay be disposed radially under an ablation element structure. The one ormore irrigation ports may be disposed between windings of the distal andproximal ablation electrodes, and wherein none of the one or moreirrigation ports may be disposed radially under an ablation elementstructure. In a side view, an irrigation port may be disposed betweenevery adjacent pair of ablation element helical sections.

In this aspect the ablation element may comprise first and secondablation elements, each of which may be electrically configured to beindependently energized in monopolar mode.

In this aspect the ablation element may comprise first and secondablation elements that are electrically configured to be energized inbipolar mode.

In this aspect the distal section may be no more than 7 cm from a distaltip of the ablation catheter.

In this aspect the ablation element may be adapted to create an ablationhaving a length in a range of 10 to 25 mm, such as 15 mm to 20 mm.

In this aspect the distal section may be adapted for flexibly traversinga bend from an azygos vein to a T9, T10, or T11 intercostal vein.

In this aspect the catheter may further comprise a guidewire lumenwithin the elongate shaft and having a distal port at a distal tip ofthe catheter.

In this aspect the ablation element may comprise one or more of an RFablation electrode, a coiled wire electrode, a laser cut RF electrode, aRF electrode printed with conductive ink, a RF electrode on anexpandable balloon (e.g., conductive ink, flexible circuits,), aconductive membrane RF electrode, a RF electrodes on an expandable cageor mesh, an ultrasound ablation transducer, an electroporationelectrodes, an cryoablation element, or a virtual RF electrode.

In this aspect the ablation element may be adapted and configured todeliver ablation energy circumferentially to create a circumferentiallesion.

One aspect of the disclosure is an ablation catheter for ablating agreater splanchnic nerve, comprising: an elongate shaft, an electricallyconductive flexible ablation element (optionally distal and proximalcoiled elements) carried by a distal section or region of the elongateshaft, and a plurality of irrigation ports in the distal section of theelongate shaft. The electrically conductive flexible ablation elementmay have an axial length (e.g., from a proximal end to a distal end)from 5 mm-25 mm.

In this aspect, an elongate shaft may have a length such that at least aportion of a distal section of the elongate shaft can be positioned in aT9, T10, or T11 intercostal vein. In this aspect, an electricallyconductive flexible ablation element may comprise distal and proximalelectrically conductive flexible ablation elements (optionally coiled)carried by the elongate shaft distal section.

In this aspect, a first subset of the plurality of irrigation ports maybe disposed between windings of an electrically conductive flexibleablation element, such as an RF electrode, which may be a firstelectrode or a second electrode. A subset of the plurality of irrigationports may be distal to the electrically conductive flexible ablationelement. A subset of the plurality of irrigation ports may be disposedaxially between distal and proximal ablation elements.

In this aspect, the elongate shaft may be void of or free of irrigationports between at least one winding at distal and/or proximal ends of anelectrically conductive flexible ablation, optionally void of or free ofirrigation ports between at least one winding at distal and/or proximalends of first and second coiled electrodes.

In this aspect, an electrically conductive flexible ablation element mayinclude distal and proximal coiled electrodes. Distal and proximal endsof each of distal and proximal electrodes may comprise a coil with avarying pitch.

In this aspect, distal irrigation ports may be within 2 mm of a distalend of an electrically conductive flexible ablation, which may be adistal end of a distal ablation element. In some instances, the numberof distal irrigation ports may be from two to four, or more. Distalirrigation ports herein may be axially aligned, such as shown inexemplary FIG. 8E.

In this aspect, distal and proximal electrically conductive flexibleablation elements may be are axially spaced no more than 2 mm apart,optionally no more than 1.5 mm apart.

In this aspect, central irrigation ports between distal and proximalablation may include from two to four ports, or more, and may be axiallyaligned, such as shown in exemplary FIG. 8E.

In this aspect, the plurality of irrigation ports may have a combinedand total area in a range of 1.51e-4 to 1.08e-3 in².

In this aspect, a diameter of all of the plurality of irrigation portsmay be in a range of 0.002″ to 0.009″.

In this aspect, the quantity of the plurality of irrigation ports may bein a range of 17 to 344.

In this aspect, the plurality of irrigation ports may have a size andquantity such that a Weber number is in a range of 0.4-53 whenirrigation fluid is delivered from the plurality of irrigation ports,optionally at a rate of 15 ml/min to 50 ml/min, and optionally withsaline.

In this aspect, the distal section may have a distal length from 60 mmto 70 mm and may be sufficiently flexible to be advanced from an azygousvein into an intercostal vein. In this aspect, the elongate shaft mayalso have a central transition section proximal to the distal section,the central section optionally having a central length from 15 mm to 25mm and optionally having a central stiffness and that is greater than adistal stiffness of the distal section. In this aspect, the elongateshaft may have a proximal section proximal to a central section, theproximal section optionally having a length that is greater than thedistal length and greater than the central length, the proximal sectionoptionally having a proximal stiffness that is greater than the centralstiffness and greater than the distal stiffness. A central section inthis aspect may be immediately axially adjacent and proximal to thedistal section. A proximal section in this aspect may be immediatelyaxially adjacent and proximal to a central section. In this aspect, adistal section may have a durometer from 50 D to 60 D, optionally 55 D.In this aspect, a central section may have a durometer from 60 D to 70D, optionally from 60 D to 65 D. In this aspect, a proximal section mayhave a distal end not closer than 50 mm from a distal end of thecatheter. A proximal section in this aspect may have a distal end thatis from 75 mm to 100 mm away from a distal end of the catheter, and mayoptionally extend to a proximal end of the elongate shaft. In thisaspect, a proximal section may include a braided reinforcing structuretherein, and distal and central sections may optionally be free of abraided reinforcing structure. In this aspect, a proximal section may asa durometer from 70 D to 80 D, optionally from 70 D to 75 D.

In this aspect, a distal section of an elongate shaft may have a linearor straight configuration (such as shown in exemplary FIG. 8E) and mayhave an outer diameter from 1.5 mm to 3 mm when the distal section isoutside of a sheath.

Any first and second ablation elements in this aspect may have coiledconfigurations, such as those shown in exemplary FIG. 8E.

In this aspect, the distal section may include a plurality of irrigationports having a helical configuration. There may be multiple sets ofports, each of which has a separate helical configuration, such as shownin the multiple sets of irrigation ports shown in exemplary FIG. 8E. Themultiple sets may be between distal and proximal end of any particularelectrode, such as shown in exemplary FIG. 8E.

In this aspect, a distal section of the shaft may have a distaldiameter, a central section may have a central diameter, and a proximalsection may have a proximal diameter, the distal diameter optionallyless than the central diameter and the central diameter optionally lessthan the proximal diameter. In this aspect, a distal diameter may befrom 1.5 mm to 2.5 mm, optionally 2 mm. A central diameter may be from2.0 mm to 3.0 mm, optionally 2.5 mm. A proximal diameter may be from 2.5mm to 3.5 mm, optionally 3 mm.

One aspect of this disclosure is related to tracking or calculating howmuch volume of liquid has been delivered through a catheter and into apatient. This aspect may include a computer executable method that isadapted to calculate an accumulated volume of liquid that has beendelivered through a catheter to a patient while excluding (or notincluding) from the accumulated volume liquid that may be deliveredthrough the catheter but not into the patient's vasculature. The methodmay include initiating a method that calculates an accumulated volume ofliquid that has been delivered from outside of a catheter, through thecatheter, and into a patient, and in response to an exclusion event thatis indicative of the catheter not being inside the patient, stopping themethod that calculates the accumulated volume of liquid to avoidincluding a volume of fluid that is not delivered into the patient'svasculature from being included in the accumulated volume.

In this aspect, an exclusion event may comprise an operator action thatcauses the method to be stopped.

In this aspect, an exclusion event may comprise an automatic action thatcauses the method to be stopped.

In this aspect, a method that calculates an accumulated volume of liquidmay comprise calculating an accumulated volume by multiplying a flowrate by an elapsed time. A flow rate may be determined by multiplying avolume per pulse by pulses per second.

This aspect may also include calculating or tracking an accumulatedvolume of the liquid that is not delivered into the patient'svasculature when it is determined that the catheter is not in thepatient's vasculature.

In this aspect, an exclusion event may optionally comprise an impedancemeasurement or calculation that is outside of a range, or higher than ahigh threshold, for example. An exclusion event may comprise animpedance measurement or calculation that is above 700 to 900 Ohms in amonopolar mode, for example. An exclusion event may comprise animpedance measurement or calculation that is above 300 to 600 Ohms inbipolar mode, for example. An exclusion event may comprise an impedancemeasurement or calculation that is outside of 60 to 80 Ohms, forexample.

In this aspect, an exclusion event may comprise an impedance measurementor calculation that determines if the catheter is out of the body.Initially, the catheter is out of the body and when a low threshold iscrossed the algorithm may be adapted to determine that the catheter haspassed into the body, wherein pumped saline is included in theaccumulation calculation. When the catheter is determined to be in thebody and a high threshold is passed, the algorithm may be adapted todetermine that the catheter has passed from in the body to out of thebody, wherein pumped saline is excluded. An exclusion event may comprisea determination that the catheter is out of the body. If the catheter isout of the body an exclusion event may comprise an impedance measurementthat is higher than a low threshold. If the catheter is in the body anexclusion event may comprise an impedance measurement that is higherthan a high threshold.

In this aspect, a method that calculates an accumulated volume of liquidmay continue uninterrupted until an exclusion event occurs.

In this aspect, the liquid may be saline.

Any method in this aspect may store on an external energy deliveryconsole of an ablation system, which may be any of the external systemsdescribed herein that are adapted to be placed in operable communicationwith any of the ablation catheters herein.

One aspect of the disclosure is related to methods of deliveringablative energy to tissue, such as tissue surrounding an intercostalvein. The methods may include delivering waveforms from any of theexternal systems herein to any of the suitable ablation cathetersherein, and may include the external system receiving information fromany of the suitable ablation catheters herein.

In this aspect, a method may include delivering from a power module(e.g. part of an external system) to a first electrode a first waveformof ablative RF energy with an initial power from 15-50, delivering fromthe power module to a second electrode a second waveform of ablative RFenergy with an initial power from 15-50 W, receiving informationindicative of at least one of sensed temperature or measured impedance,determining if at least one of the sensed temperature or the measuredimpedance is at or above a limit, if at least one of the sensedtemperature or the measured impedance is at or above a threshold limit,decreasing the power of at least one of the first waveform and thesecond waveform.

The methods in this aspect may be used with any suitable catheterherein. For example, a first waveform may be delivered to a firstelectrode (optionally coiled), and a second waveform may be delivered toa second electrode (optionally coiled).

In this aspect, if at least one of the sensed temperature or themeasured impedance is at or above a threshold limit, and a minimumtherapy time has not yet passed, the reducing step may comprise reducingthe power of at least one of the first waveform and second waveform to asecondary power less than the initial power. In this aspect, a secondarypower may be from 5-10 W less than any initial power.

In this aspect, if at least one of the sensed temperature or themeasured impedance is at or above a threshold limit, and a minimumtherapy time has passed, the reducing step may comprise reducing thepower of at least one of the first waveform and second waveform to asecondary power that is from 0 W to 1 W.

In this aspect, the first and second waveforms may be multiplexed.

In this aspect, the first and second waveforms may be asynchronous.

In this aspect, delivering from a power module to a first electrode maycomprise delivering from a power module to a first electrode a firstwaveform of ablative RF energy with an initial power of 25 W. Deliveringfrom a power module to a second electrode may comprise delivering from apower module to the second electrode a second waveform of ablative RFenergy with an initial power of 25 W.

In this aspect, the first and second waveforms may be alternatingwaveforms that alternate between an ablative power amplitude and anon-ablative power amplitude. A non-ablative power amplitude in thisaspect may be in a range of 0 W to 1 W.

In this aspect, the determining step may comprise determining if thesensed temperature is at or above 40° C. to 95° C., optionally at orabove 90° C.

In this aspect, the receiving step may comprise receiving informationfrom a temperature sensor associated with a first electrode, such as anyof the coiled electrodes herein. In this aspect, the receiving step maycomprise receiving information from a second temperature sensorassociated with a second electrode, such as any of the coiled electrodesherein.

In this aspect, the determining step may comprise determining if ameasured impedance is at or above 200 to 500 ohms, optionally at orabove 500 ohms.

In this aspect, reducing the power of at least one of the first waveformand the second waveform may comprise reducing the power of at least oneof the first waveform and the second waveform to a power from 10 W to 30W, optionally 20 W.

In this aspect, reducing the power of at least one of the first waveformand the second waveform may comprise reducing the power of at least oneof the first waveform and the second waveform by a power decrement from1 W to 30 W, optionally from 5-10 W.

In this aspect, at least one of the first and second waveforms may havea pulse width in a range of 0.5 seconds to 4 seconds.

In this aspect, the power of the first waveform may be decreased if asensed temperature corresponding to a first electrode is at or above thelimit, and wherein the power of the second waveform may be decreased ifthe sensed temperature corresponding to a second electrode is at orabove the limit.

In this aspect, the delivering step may occur for at least 60 seconds.

In this aspect, the delivering step may occur with a default setting tooccur from 30 seconds to 180 seconds.

Any method in this aspect may further comprise delivering irrigationfluid to an ablation catheter at a flow rate in a range of 10 to 30ml/min. Delivering irrigation fluid to an ablation catheter may includedelivering fluid to, though, and out of any of the ablation cathetersherein, including any and all of the description of the irrigation portsfrom which irrigation fluid may be delivered into the subject.

One aspect of the disclosure is related to external devices (which mayinclude one or more separate components) that are adapted for use withany of the ablation catheters herein. External devices as used hereingenerally refers to one or more components of a system that remainoutside of a subject, such as a power module, energy generator, etc. Theexternal devices herein may be adapted to be coupled to or with any ofthe ablation catheters herein to create operable communicationtherebetween. External devices herein may be referred to as externalsystems, and it is understood that this refers to the external nature ofthe one or more components. An ablation catheter and one or moreexternal components may together be referred to herein as a system. Anyfeature of this aspect may be incorporated with the previous aspectdescribed herein that is related to delivering ablative energy, and viceversa. For example, any of the methods set forth in the previous aspectmay be stored in one or more memories on any of the external devices inthis aspect of the disclosure, and may be used with any of the ablationcatheters in this aspect.

This aspect may include an external device or system that is adapted foruse with an ablation catheter that includes first and second ablationelectrodes. The external device may comprise a power output module thatadapted to deliver a first waveform of ablative RF energy with aninitial power from 15-50 W and a second waveform of ablative RF energywith an initial power from 15-50 W. The external device may also includea module adapted to receive information indicative of at least one ofsensed temperature or measured impedance and determine if at least oneof the sensed temperature or the measured impedance is at or above alimit, and if at least one of the sensed temperature or the measuredimpedance is at or above a threshold limit, causing the power outputmodule to decrease the power of at least one of the first waveform andthe second waveform.

In this aspect, the module may comprise at least one of a temperaturelimit module or an impedance limit module.

One aspect of this disclosure is related to delivering irrigation fluidto an ablation catheter. This aspect may include a method of deliveringablation energy and irrigation fluid to a catheter for ablating agreater splanchnic nerve, wherein the method includes positioning anablation catheter in an intercostal vein, delivering ablative energy toone or more ablation elements carried by a distal region of an ablationcatheter, ablating a greater splanchnic nerve outside of the intercostalvein, and delivering irrigation fluid out of a plurality of irrigationports in the distal region or section of the ablation catheter at a ratefrom 15 ml/min-50 ml/min.

Any feature of this aspect of the disclosure may be included orincorporated with any step or steps of any other aspect, includingaspects related to delivering ablative energy using any of the ablationcatheters herein.

In this aspect, delivering the irrigation fluid may comprise deliveringirrigation fluid out of a plurality of irrigation ports in the distalregion of the ablation catheter at a rate of 30 ml/min.

In this aspect, delivering the irrigation fluid may comprise deliveringthe irrigation fluid out of 17 to 344 irrigation ports in the distalregion or section of the catheter.

In this aspect, delivering the irrigation fluid comprises delivering theirrigation fluid out of a plurality of distal irrigation ports, thedistal irrigation ports being disposed distal to the one or moreablation elements.

In this aspect, delivering the irrigation fluid may comprise deliveringthe irrigation fluid out of a plurality of central irrigation ports, thecentral irrigation ports disposed between a proximal ablation elementand a distal ablation element.

In this aspect, delivering the irrigation fluid may comprise avoidingdelivering the irrigation fluid out of any part of the distal region orsection of the shaft that is proximal to the one or more ablationelements, optionally due to the absence of any irrigation ports proximalto the one or more ablation elements.

In this aspect, delivering ablative energy may comprises deliveringenergy at a power from 15 W-50 W, optionally at 35 W.

In this aspect, delivering the irrigation fluid may comprise deliveringirrigation fluid distal to the one or more ablation elements and notdelivering irrigation fluid proximal to the one or more ablationelements.

In this aspect, delivering the irrigation fluid may comprise deliveringirrigation fluid out of a plurality of irrigation ports, wherein theplurality of irrigation ports optionally having a combined area in arange of 1.51e-4 to 1.08e-3 in².

In this aspect, a diameter of the plurality of irrigation ports may bein a range of 0.002″ to 0.009″.

In this aspect, delivering the irrigation fluid out of the plurality ofirrigation ports at a rate from 15 ml/min-50 ml/min may create a Webernumber in a range of 0.4-53.

In this aspect, delivering the ablative energy may comprise deliveringthe ablation energy to first and second coiled ablation elements thatare axially spaced apart on the shaft.

In this aspect, delivering irrigation fluid may comprise delivering theirrigation fluid out of at least some of the plurality of ports that aredisposed between windings of first and second coiled ablation elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings included herewith are for illustrating various examples ofarticles, methods, and apparatuses of the present specification and arenot intended to limit the scope of what is taught in any way. In thedrawings:

FIG. 1 is an isometric view schematic illustration of an ablationcatheter positioned in an intercostal vein for ablation of a thoracicsplanchnic nerve.

FIG. 2 is a transverse view schematic illustration of an ablationcatheter positioned in an intercostal vein and a centered azygos vein.

FIG. 3 is a transverse view schematic illustration of anatomy showing aright-biased azygos vein.

FIG. 4 is a transverse view schematic illustration of anatomy showing aleft-biased azygos vein.

FIG. 5 is a transverse view schematic illustration of anatomy showing arange of position of azygos veins and a range of position of a rightGSN.

FIG. 6 is an AP fluoroscopic image of a patient's T8 to T12 thoracicregion.

FIG. 7 is an RAO30 fluoroscopic image of a patient's T8 to T12 thoracicregion.

FIG. 8A is a schematic illustration of an ablation catheter with twocoiled RF electrodes.

FIG. 8B is a schematic illustration of an ablation catheter with twocoiled RF electrodes and a distal deployable element.

FIG. 8C is a schematic illustration of a first, second and third sectionof a catheter shaft.

FIG. 8D is a schematic illustration of a distal portion or section of anablation catheter having irrigation holes arranged in a helical patternbetween windings of a helical electrode and an irrigation hole distal tothe distal electrode.

FIG. 8E is a schematic illustration of a distal portion of an ablationcatheter having irrigation holes arranged in a helical pattern betweenat least some windings of a helical electrode and a plurality ofirrigation holes distal to a distal electrode and between proximal anddistal electrodes.

FIG. 9 is a schematic illustration of an ablation catheter with twocoiled RF electrodes, a distal deployable element, and a proximaldeployable element.

FIG. 10 is a schematic illustration of an ablation catheter with twocoiled RF electrodes, a distal deployable element, a proximal deployableelement, and a middle deployable element.

FIG. 11 is a schematic illustration of an ablation catheter with an RFelectrode comprising expandable wire struts.

FIG. 12 is a schematic illustration of an ablation catheter with an RFelectrode comprising an expandable balloon with an RF electrode on itssurface.

FIGS. 13A and 13B are schematic illustrations of an ablation catheterwith an RF electrode comprising an expandable balloon with an RFelectrode made from conductive ink on its surface.

FIG. 14 is a schematic illustration of an ablation catheter with an RFelectrode comprising an expandable balloon with an RF electrode on itssurface in a zig-zag pattern.

FIG. 15 is a schematic illustration of an ablation catheter with an RFelectrode in a cavity defined by a membrane.

FIG. 16 is a schematic illustration of an ablation catheter with aplurality of RF electrode sections on a tapered shaft

FIGS. 17A and 17B are schematic illustrations of an ablation catheterwith RF electrode pads on an expandable balloon.

FIG. 18 is a schematic illustration of an ablation catheter withultrasound transducers.

FIG. 19 includes plots of RF Power delivered to a first electrode and asecond electrode as well as temperature monitored by sensors associatedwith the first and second electrodes and bioelectric impedance monitoredfrom the first and second electrodes on the same time axis.

FIG. 20 is an exemplary machine state diagram of an exemplary salinetracking algorithm.

FIG. 21A is a schematic illustration of an ablation catheter with flathelical electrodes.

FIG. 21B is a schematic illustration of an ablation catheter with flathelical electrodes.

DETAILED DESCRIPTION

The disclosure herein is generally related to methods of treating atleast one of heart failure and hypertension by increasing splanchniccapacitance. Some approaches include systems, devices, and methods fortransvascular (e.g., transvenous) ablation of target tissue to increasesplanchnic venous capacitance or venous compliance. The devices andmethods may, in some examples, be used for ablating a splanchnic nerveto increase splanchnic capacitance. For example, the devices disclosedherein may be advanced endovascularly to a target vessel or plurality ofvessels in the region of a thoracic splanchnic nerve (“TSN”), such as apreganglionic greater splanchnic nerve (“GSN”), lesser splanchnic nerve,or least splanchnic nerve or one of their roots (a TSN nerve root). Thetarget vessel may be, for example, an intercostal vein or an azygos vein(or both) or a vein of the azygos vein system, preferably, one or moreof the lowest (i.e., most caudal) three intercostal veins (which may beT9, T10, or T11).

FIG. 1 shows a patient's thoracic spine, including T12 (62), T11 (63),T10 (64), and T9 (65) vertebrae, intervertebral discs, a sympathetictrunk 54, an azygos vein 50, a right T11 intercostal vein 55, a rightT10 intercostal vein 56, a right T9 intercostal vein 66, GSN roots 53,and a fully-formed GSN 52. The lesser and least splanchnic nerves andtheir roots are omitted for simplicity. A primary objective of theproposed procedure is to ablate the GSN or its roots as will bediscussed in detail herein. It is noted that ablation of the lesser orleast splanchnic nerves or their roots may also have therapeutic effectsand may be a procedural objective. A delivery sheath 80 is shownpositioned in the azygos vein and an ablation catheter 81 is showndelivered through the sheath and passing from the azygos vein into theT11 intercostal vein. The sympathetic trunk runs substantially parallelto the spine, consistently passing close to each costovertebral joint 61(see FIG. 2). On the right side of the body the GSN roots branch fromthe sympathetic trunk, typically cranial to the T9 vertebra, andconverge to form the GSN, which travels at an angle from the sympathetictrunk toward the anterior-center of the spine and is positioned anteriorto the intercostal veins between the intercostal veins and parietalpleura 60 (see FIG. 2). The azygos vein 50 travels along the anterior ofthe spine and may be somewhat straight and parallel to the axis of thespine as shown in FIG. 1. However, the precise position of the azygosvein relative to the spine is variable from patient to patient and atdifferent vertebral levels. At the T9, T10, and T11 vertebral levels theazygos vein 50 may be centered with respect to the midline of thevertebra 69 as shown in FIG. 2, may be a right-biased azygos vein 50Rwith respect to the midline of the vertebra 69 as shown in FIG. 3, or bea left-biased azygos vein 50L with respect to the midline of thevertebra 69 as shown in FIG. 4. Cadaver studies conducted by the authorsindicate that the range of azygos position relative to the center of thespine at the T9, T10, and T11 levels is within 10 mm to the left orright of center for a large majority of people. FIG. 5 shows aleft-biased azygos vein 50L, a right-biased azygos vein 50R, and acentered azygos vein 50C along with the range 67 of the azygos veinrelative to the center of the spine 69. Furthermore, the preciseposition of the right GSN from patient to patient is somewhat variableincluding where it originates from the sympathetic trunk, the angle atwhich it travels, and its destination relative to the spine. Thus, theposition of the GSN relative to the vertebra at T9, T10 and T11 canvary. Cadaver studies conducted by the authors indicate that the rangeof right side GSN position relative to the center of the vertebra at theT9, T10 and T11 levels is from 0 mm to 25 mm to the right of center 69as shown by the range box 68 in FIG. 5.

An endovascular approach to transvascularly ablate a TSN, particularly aGSN may involve one or more of the following steps: accessing venousvasculature at the patient's jugular vein or femoral vein with an accessintroducer sheath (e.g. 12 F); delivering a delivery sheath (e.g., 9 Fsheath) to an azygos vein (e.g., to one or two thoracic levels above thetarget intercostal vein); optionally, delivering contrast agent throughthe sheath to show location of veins on fluoroscopy; optionally,delivering a guidewire (e.g., 0.014″ guidewire) through the deliverysheath and into a targeted T9, T10, or T11 intercostal vein; anddelivering an ablation catheter through the delivery sheath to theazygos vein, optionally over the guidewire, positioning an ablationelement in an intercostal vein, azygos vein or both; and aligning aradiopaque marker on the ablation catheter with an anatomical landmark(or positioning it relative thereto) to position an ablation element ina region that maximizes efficacy of ablating a target TSN/GSN whileminimizing risk of injuring one or more non-target structures.

Some important anatomical structures in the vicinity of this region thatshould not be injured include the sympathetic trunk 54, vagus nerve,thoracic duct, and esophagus. Therefore, to ensure safety an ablationzone should be contained within a safe region that does not injure suchstructures. Due to the variability of position of the azygos vein andGSN relative to the T9, T10 and T11 vertebrae, the relative position ofthe GSN with respect to the intercostal vein or azygos vein in which anablation element is positioned is also variable.

Bones, blood vessels if injected with radiopaque contrast medium, andmedical devices if made from radiopaque material, are visible onfluoroscopy but nerves are not. An ablation device designed fortransvascular (e.g., transvenous) ablation of a TSN (e.g., GSN) from anintercostal vein, azygos vein, or both along with procedural steps maybe provided to ensure efficacious ablation of the TSN (e.g., GSN) whileensuring safety. The procedural steps may include fluoroscopic imagingto position the ablation element(s) of the ablation catheter withrespect to boney or vascular structures.

In a first embodiment of a method of ablating a right GSN an ablationcatheter having a proximal radiopaque marker 136, a distal radiopaquemarker 130, an ablation element 131 or plurality of ablation elements132, 133, and an optional gap 135 between the ablation element and thedistal radiopaque marker is advanced from an azygos vein 50 into anintercostal vein 55 at one of the lower three thoracic levels (e.g., T9,T10, T11). The C-Arm is placed in Anterior-Posterior (AP) orientation.The proximal radiopaque marker 136 is aligned with the midline of thevertebra 69, which is possible if the azygos vein 50 is centered orleft-biased. If the azygos vein 50 is left-biased the proximalradiopaque marker will need to be advanced into the intercostal vein toalign it with the midline of the vertebra 69. If the azygos vein isright-biased the proximal radiopaque marker 136 will not be able to beplaced at the midline of the vertebra 69. In this case the proximalradiopaque marker 136 may be placed at the ostium of the intercostalvein, which will be to the right of midline 69. Optionally, the positionof a distal radiopaque marker 130 relative to the costovertebral jointmay be assessed (e.g., with the C-Arm in a RAO orientation) to ensurethe sympathetic trunk is not at risk of injury, for example withpatients who are very small and have an extreme right-biased azygosvein. The C-Arm may be obliquely angled to the right (RAO orientation)to maximize the 2D projection of the section of intercostal vein betweenthe costovertebral joint 61 and anterior midline of the vertebra 69(FIG. 7). For example, the C-arm may be positioned with a Right AnteriorOblique (RAO) angle in a range of 20° to 70° from AP (e.g., in a rangeof 30° to 60°, in a range of 35° to 55°, about 30°, at an angle thatmaximizes projected distance between the proximal and distal ROmarkers). With this view the user may check to make sure the distalradiopaque marker is not too close to the costovertebral joint 61. Forexample, if the distal radiopaque marker is positioned directly distalto the ablation element a distance of at least 3 mm (e.g., at least 5mm) may be chosen to ensure the sympathetic trunk is not injured. Inanother example, if the distal radiopaque marker is positioned distal tothe ablation element with a known space between them the distalradiopaque marker may be aligned with the costovertebral joint orproximal to it to ensure safety of the sympathetic joint. If the distalradiopaque marker is too close to or beyond the costovertebral joint thecatheter may be pulled back until an acceptable distance between thedistal radiopaque marker and the costovertebral joint is seen, which mayplace the proximal radiopaque marker in the azygos vein especially ifthe azygos vein is right biased. If the ablation element is comprised ofa plurality of ablation elements (e.g., two) an ablation may first beperformed from the more proximal ablation element prior to pulling thecatheter back to appropriately place the distal radiopaque markerrelative to the costovertebral joint. Then a subsequent ablation may bemade from the more distal ablation element.

In a second embodiment of a method of ablating a right GSN an ablationcatheter having a proximal radiopaque marker 136, a distal radiopaquemarker 130, an ablation element 131 or plurality of ablation elements132, 133, and an optional gap 135 between the ablation element and thedistal radiopaque marker is advanced from an azygos vein 50 into anintercostal vein 55 at one of the lower three thoracic levels (e.g., T9,T10, T11). The C-Arm is placed in Anterior-Posterior (AP) orientation.The proximal radiopaque marker 136 is aligned with the intercostal veinostium 59. The ostium can be found for example by injecting contrastagent and viewing the vasculature on fluoroscopy or if a guidewire waspreviously positioned in a target intercostal vein a bend in theguidewire or ablation catheter may indicate the location of the ostium.If the azygos vein is left-biased the catheter is advanced distal to theostium to align the proximal radiopaque marker 136 with the midline ofthe vertebra 69. In this placement strategy the proximal radiopaquemarker 136 will be aligned with the midline of the vertebra 69 if theazygos vein is left-biased or centered, and to the right of the midlineof the vertebra if the azygos vein is right-biased. Concurrently, theproximal radiopaque marker 136 will be aligned with the ostium if theazygos vein is right-biased or centered, and at the midline of thevertebra 69 if the azygos vein is left-biased. Optionally, the positionof a distal radiopaque marker 130 relative to the costovertebral jointmay be assessed (e.g., with the C-Arm in a RAO orientation) to ensurethe sympathetic trunk is not at risk of injury, for example withpatients who are very small and have an extreme right-biased azygosvein. The C-Arm may be obliquely angled to the right (RAO orientation)to maximize the 2D projection of the section of intercostal vein betweenthe costovertebral joint 61 and anterior midline of the vertebra 69(FIG. 7). For example, the C-arm may be positioned with a Right AnteriorOblique (RAO) angle in a range of 20° to 70° from AP (e.g., in a rangeof 30° to 60°, in a range of 35° to 55°, about 30°, at an angle thatmaximizes projected distance between the proximal and distal ROmarkers). With this view the user may check to make sure the distalradiopaque marker is not too close to the costovertebral joint 61. Forexample, if the distal radiopaque marker is positioned directly distalto the ablation element a distance of at least 3 mm (e.g., at least 5mm) may be chosen to ensure the sympathetic trunk is not injured. Inanother example, if the distal radiopaque marker is positioned distal tothe ablation element with a known space between them the distalradiopaque marker may be aligned with the costovertebral joint orproximal to it to ensure safety of the sympathetic joint. If the distalradiopaque marker is too close to or beyond the costovertebral joint thecatheter may be pulled back until an acceptable distance between thedistal radiopaque marker and the costovertebral joint is seen, which mayplace the proximal radiopaque marker in the azygos vein especially ifthe azygos vein is right biased.

In a third embodiment of a method of ablating a right GSN an ablationcatheter having a distal radiopaque marker 130, an ablation element 131or plurality of ablation elements 132, 133, and a gap 135 between theablation element and the distal radiopaque marker is advanced from anazygos vein 50 into an intercostal vein 55 at one of the lower threethoracic levels (e.g., T9, T10, T11). The C-Arm is obliquely angled tothe right to maximize the 2D projection of the section of intercostalvein between the costovertebral joint 61 and anterior midline of thevertebra 69 (FIG. 2). For example, the C-arm may be positioned with aRight Anterior Oblique (RAO) angle in a range of 20° to 70° from AP(e.g., in a range of 30° to 60°, in a range of 35° to 55°, about 30°, atan angle that maximizes projected distance between the proximal anddistal RO markers). A fluoroscopy image in an anterior-posterior (AP)view is shown in FIG. 6. In comparison a fluoroscopy image in a RAO 300is shown in FIG. 7. The catheter is advanced to align the distalradiopaque marker 130 with the costovertebral joint 61. Since thesympathetic trunk 54 is next to the costovertebral joint 61 the gapbetween the distal radiopaque marker and the ablation element may ensurethe sympathetic trunk is not injured. The gap may be for example alength in a range of 0 to 25 mm (e.g., a range of 3 to 25 mm, a range of5 to 25 mm, a range of 5 to 20 mm). Optionally, an inflatable balloon134 may be positioned on the catheter shaft within the gap, which mayhelp to anchor the catheter or contain ablation energy proximal to theballoon. Optionally, the catheter shaft 138 distal to the ablationelement may be narrower or more flexible than the remainder of the shaftto facilitate delivery through the narrower distal portion of theintercostal vein. Optionally, the ablation element(s) has a lengthcapable of ablating to the anterior midline of the vertebra 69 when thedistal radiopaque marker is aligned with the costovertebral joint. Forexample, the ablation element(s) may have a total length in a range of 5to 25 mm (e.g., in a range of 10 to 25 mm, in a range of 15 to 20 mm).The ablation catheter may have a proximal radiopaque marker located justproximal to the ablation element(s). Optionally, prior to deliveringablation energy a user may image the proximal radiopaque marker toensure it is at the anterior midline of the vertebra 69. If the proximalradiopaque marker is to the left of the midline 69, for example if thepatient is extremely small, there may be a risk of injuring a non-targettissue such as the thoracic duct or esophagus. To mitigate this risk acatheter with a smaller sized ablation element may be used or if theablation element is made of a plurality of ablation elements only theelements between the midline 69 and distal radiopaque marker may beactivated for ablation. Conversely, if the proximal radiopaque marker isto the right of the midline 69, for example if the patient is extremelylarge, there may be a risk of missing the GSN. To mitigate this riskanother ablation may be performed at another intercostal level or withinthe same intercoastal vein with the position of the ablation elementretracted until the proximal radiopaque marker is aligned with themidline 69.

In a fourth embodiment of a method of ablating a right GSN an ablationcatheter having an ablation element 131, which may include a pluralityof ablation elements, a distal radiopaque marker located at a distal endof the ablation element(s), and a proximal radiopaque marker located ata proximal end of the ablation element(s) is advanced from an azygosvein into an intercostal vein at one of the lower three thoracic levels(e.g., T9, T10, T11). The C-Arm is obliquely angled to the right tomaximize the 2D projection of the section of intercostal vein betweenthe costovertebral joint 61 and anterior midline of the vertebra 69(FIG. 5). For example, the C-arm may be positioned with a Right AnteriorOblique (RAO) angle in a range of 25° to 65° from AP (e.g., in a rangeof 30° to 60°, in a range of 35° to 55°, about 30°). The catheter isadvanced to align the distal radiopaque marker with a position relativeto the costovertebral joint and the opposing edge of the vertebral bodyin the oblique view. For example, the distal radiopaque marker may bealigned with a point that is midway between the costovertebral joint andthe opposing edge of the vertebral body in the oblique view. Theablation element(s) may have a total length expected to cover the GSNposition range 68 in most patients. Similar to the previously describedmethods, the proximal end of the ablation element(s) may be at theanterior midline of the vertebra 69 or to the left in centered orleft-biased azygos situations and may be in the azygos vein inright-biased azygos situations. Ablation energy may be delivered fromthe ablation element(s) to ablate the range without moving the catheter.Optionally, the catheter may be moved to another intercostal level and asecond ablation may be made using the same method steps.

Performing any of the exemplary embodiments of placement strategydisclosed above, when the ablation element 131 has a total length lessthan 30 mm (e.g., less than 25 mm, less than 20 mm, about 15 mm) it isexpected that in a large majority of patients the sympathetic trunk willbe spared from injury even if the azygos vein is right-biased.Additionally, when performing the methods herein, when the ablationelement 131 has a total length greater than or equal to 15 mm it isexpected that in a large majority of patients the GSN will be ablated.Therefore, the ablation element 131 may have a total length in a rangeof 15 mm to 30 mm to be effective and safe for a large majority ofpatients using these placement strategies. However, smaller ablationelement total length may be suitable for exceptional patients. Forexample, the ablation element may have a total length in a range of 5 to25 mm (e.g., in a range of 10 to 20 mm, or in a range of 10 to 15 mm).

As used herein, ablation element may refer to a single structure or aplurality of structures. For example, as used herein, ablation elementmay include a plurality of ablation electrodes that are axially spacedapart, and each of which may be adapted to facilitate the delivery ofablation energy.

Once acceptable ablation element placement is achieved, for exampleusing one of the exemplary embodiments of placement strategy herein,ablation energy may be delivered from the ablation element or pluralityof ablation elements without having to move the catheter. Ablationenergy may be delivered from the ablation element to ablate tissuecircumferentially around the intercostal vein a depth in a range of 2 mmto 10 mm (e.g., a range of 2 mm to 8 mm, a range of 3 mm to 8 mm, about5 mm). Optionally, the procedure may be repeated at another thoraciclevel (e.g., a more cranial level, a more caudal level, another of T9,T10, T11 intercostal veins on the same side of the patient) especiallyif the azygos is right biased. Alternatively or in addition to havingdistal and proximal radiopaque markers at both ends of an ablationelement or plurality of ablation elements, the ablation element(s)itself may be radiopaque and the same methods herein may be used toposition the distal or proximal end of the ablation element(s) relativeto anatomical landmarks (e.g., midline of the spine, costovertebraljoint, etc.). The phrase radiopaque marker as used herein may thusdescribe an ablation element if the ablation element is radiopaque. Insome alternative embodiments, a radiopaque markers may comprise arelatively longer radiopaque marker positioned under or next to one ormore ablation elements wherein the proximal end of the long radiopaquemarker is at least aligned with the proximal end of the ablation elementor extending proximal of the ablation element by up to 3 mm and thedistal end of the long radiopaque marker is at least aligned with thedistal end of the ablation element or extending distal to the ablationelement by up to 3 mm.

With any of the exemplary embodiments of placement strategy disclosedabove, there may be situations when a portion of the ablation element(s)is in the azygos vein while the remainder is in the intercostal vein, inparticular when the ablation catheter has an ablation element orplurality of elements having a total length in a range of 10 to 25 mm.The azygos vein is larger than the intercostal vein and has greaterblood flow, which may impact the ability to create an effective ablationaround the azygos vein or even in the intercostal vein and may requiredifferent energy delivery parameters than an ablation made completely inan intercostal vein. To resolve this, the ablation catheter may have aplurality of ablation elements wherein at least one is fully positionedin an intercostal vein and the remainder may be in the intercostal veinor in the azygos vein or both. Different ablation energy deliveryparameters may be used for the different scenarios, for example higherpower or energy may be delivered to the ablation element in the azygosvein or ablation energy may only be delivered to the element(s) that arefully or partially in the intercostal vein. The location of theplurality of ablation elements may be determined with fluoroscopicimaging or by monitoring electrical impedance between each ablationelement (e.g., RF electrode) and a dispersive electrode.

Optionally, two or even three levels may be ablated, particularly if theazygos is right-biased but even if the azygos is centered orleft-biased, which may further increase efficacy.

Alternative devices and methods of use may include a shorter ablationelement that is used to create a relatively shorter ablation andrepositioned a plurality of times to create multiple ablations withinthe GSN position range 68. If the azygos is centered or left-biased allablations may be made in the intercostal vein 55 and cover the range 68.If the azygos is right-biased, ablations may be made in the intercostalvein to cover a portion of the range 68, and then ablations may be madeat another intercostal level to improve the probability of ablating theGSN. Optionally, ablations may be made from the azygos vein, which mayuse different energy delivery parameters for example, higher energy orpower.

An ablation catheter adapted to ablate a TSN (e.g., GSN) from anintercostal vein and or an azygos vein, for example using one or more ofthe embodiments of placement strategies disclosed herein, may havefeatures that allow it to be delivered transvascularly to a desiredlocation in a T9, T10, or T11 intercostal vein, be positioned relativeto anatomical features to effectively ablate a target TSN while safelyavoiding important non-target structures in a large majority ofpatients, and to deliver ablative energy capable of ablating the targetTSN. The ablation catheter and system features may allow a user toablate a TSN with relative ease and efficiency without sacrificingefficacy or safety. For example, once the ablation element(s) of thecatheter are positioned (e.g., using methods disclosed herein), ablationenergy may be delivered from a computerized ablation console with thepress of a button or at least with minimal adjustments, repositioning,dragging, torqueing of the catheter or minimal user decisions regardingenergy delivery. Even considering the variability of location of the GSN68 and azygos vein 67 (see FIG. 5), features of ablation catheters andsystems disclosed herein may allow a TSN/GSN to be ablated from oneplacement and energy delivery procedure or in some cases from anadditional placement (e.g., in another of a T9, T10, or T11 intercostalvein) and energy delivery with a high probability of success in a largemajority of patients.

An ablation catheter for transvascular ablation of a GSN may have aproximal end, a distal end, an elongate shaft therebetween, a distalsection (e.g., comprising the distal-most 7 cm), and an ablation elementon, at or carried by the distal section. The ablation element may beadapted (including sized and/or configured) to create an ablation havinga length in a range of 5 mm to 25 mm, preferably 10 to 25 mm (such as 15mm to 20 mm) and a radial depth of at least 5 mm from the vesselsurface. A handle may be located on the proximal end of the catheter tocontain electrical or fluid connections or facilitate handling of thecatheter. The elongate shaft from a strain relief region to the distaltip may have a length of 100 cm to 140 cm (such as from 110 cm to 130cm, such as about 120 cm) allowing the distal section to be deliveredfrom an arteriotomy such as a femoral vein access (or other accesslocation such as jugular vein, brachial vein, radial vein, hepatic veinor subclavian vein) to a T11 intercostal vein in a large majority ofhuman patients, or a length of 50 cm to 140 cm allowing the distalsection to be delivered from a jugular vein access to a T11 intercostalvein in most patients. To be deliverable through a 9 F delivery sheaththe catheter may have a maximum outer diameter of 3 mm (e.g., 2.5 mm, 2mm, 1.5 mm) at least in its delivery state. The catheter may optionallyhave a deployable structure that expands beyond this dimension onceadvanced from the delivery sheath and positioned in a target vessel insome embodiments. An ablation catheter for delivering an ablationelement to an intercostal vein, in particular a T9, T10 or T11intercostal vein, from an endovascular approach including approachingthe intercostal vein from an azygos vein may have a shaft with featuresthat facilitate easy tracking over a guidewire, pushability, transfer oftranslation forces from the handle of the catheter, and passing over atight bend from the azygos vein to the intercostal vein without kinking.As shown in FIG. 8C, the catheter shaft may comprise a first section340, a second section 341 and a third section 342. The first section 340may be more flexible than the second and third sections and may carrythe ablation element such as two coiled electrodes 133 and 132 as shown.This first section may have a flexibility capable of passing over thetight bend from the azygos vein to intercostal vein (e.g., having aradius of curvature >=5 mm, and angle up to 120 degrees). The firstsection may have a length in a range of 60 mm to 100 mm (e.g., about 65mm) and may be made from a single lumen Pebax® tube having a durometerfrom 50 to 60 D, such as 55 D.

The second section 341 may have a flexibility between that of the firstand third sections and function as a transition region and strain reliefto resist kinking. For example, the second section may have a length ina range of 15 mm to 25 mm (e.g., about 20 mm) and may be made from asingle lumen Pebax® tube having a durometer from 60 D-70 D, such as from60 D-65 D, such as 63 D.

The third section 342 may be at least a portion of the proximal regionof the elongate shaft and may be adapted for pushability, kinkresistance, torque transmission, and flexibility. For example, the thirdsection of the elongate shaft may span from the proximal end of thecatheter to about 85 mm (e.g., in a range of 75 mm to 100 mm) from thedistal end and may optionally have a metal wire braid embedded into anouter layer of the shaft. An example material for the third section ofthe elongate shaft may be extruded Pebax® having a durometer from 70 Dto 75 D, such as 72 D, for example. For example, the first section 340may be more flexible than the second section 341 section, which may bemore flexible than the third section 342 and flexibility may beincreased by using a lower durometer material or more flexible braidedouter layer or no braided outer layer. The maximum outer diameter of theelongate shaft, at least in a delivery state, may be in a range of 1.5to 3 mm. Optionally, as shown in FIG. 8C, the first section 340 of theshaft may be made from a tube having a smaller diameter than the secondsection 341, which in turn may have a smaller diameter than the thirdsection 342 of the shaft. For example, the first section may be made ofa tube having an outer diameter of 2 mm; the second section may be madeof a tube having an outer diameter of 2.5 mm; and the third section maybe made of a tube having an outer diameter of 3 mm. Optionally, theelongate shaft may have a tapered, soft distal tip 345, which may have alength in a range of 5 mm to 30 mm (e.g., about 8 mm), and which may besofter than the first section. Optionally, the first, second, or thirdsections of the shaft may have a lubricious coating on the exteriorsurface to further improve delivery through vasculature. A guidewirelumen may pass through the elongate shaft with an exit port 82 at thedistal tip of the shaft. The guidewire lumen may be made from, forexample, a 0.014″ ID polyimide tube located in a lumen of the shaft.

The ablation catheters may have an ablation element adapted to deliverablative energy to a target nerve up to 5 mm from the vessel surface fora total length in a range of 10 mm to 25 mm, such as 10 mm to 20 mm,such as 15 mm to 20 mm. The ablation element may be made of a pluralityof ablation elements (e.g., two) positioned within a region of the shafthaving a total length in a range of 10 mm to 25 mm, such as 10 to 20 mm,such as 15 mm to 20 mm even if the ablation elements are axially spacedapart. The ablation element(s) may include one or more of an RF ablationelectrode, a coiled wire electrode, a laser cut RF electrode, an RFelectrode printed with conductive ink, an RF electrode on an expandableballoon (e.g., made from conductive ink or flexible circuits), aconductive membrane RF electrode, an RF electrode on an expandable cageor mesh, an ultrasound ablation transducer, electroporation electrodes,a cryoablation element, or a virtual RF electrode.

The ablation element may be adapted to deliver ablation energycircumferentially, that is radially symmetric around the ablationelement and around the vessel in which the ablation element ispositioned. Although the GSN always passes anterior to the intercostalvein and azygos, it is safe and acceptable to ablate tissue around theintercostal or azygos veins, and ablating circumferentially may allowfor a simpler and faster procedure that is also less prone to user errorbecause aiming the energy delivery is not necessary. Features that mayallow for circumferential ablation may include, without limitation,ablation electrodes that expand to contact the vessel wall evenly aroundthe circumference of the vessel, ablation electrodes that are used withan electrically conductive fluid, electrically insulative balloons ordeployable structures that contain ablative energy in a segment of atarget vessel allowing it to be directed radially, ablation elementsthat direct ablation energy circumferentially such as cylindricalultrasound transducers.

In some embodiments, the ablation element is an RF electrode and salinemay be delivered to the vessel in fluid communication with the RFelectrode. An irrigation lumen in communication with irrigation portsmay located distal to the ablation element, under the ablation element(in some designs where irrigated saline can pass through the ablationelement), or in a deployable structure in some embodiments). Anirrigation lumen may be for example a lumen in the elongate shaft influid communication with a tube on the catheter's proximal end that isconnectable to a fluid source and pump.

Optionally, at least one deployable occlusive structure (e.g., balloon,bellows, wire mesh, wire braid, coated wire mesh, or coated wire braid)may be positioned on the shaft distal to the ablation element. Thedeployable structure may function to anchor the catheter in place duringenergy delivery and possibly to improve safety by avoiding ablation ofthe sympathetic trunk by providing an electrical insulator or containingsaline proximal to the deployable structure. Optionally, a deployableocclusive structure may be located just proximal to the proximal end ofthe ablation element(s) which may function to divert blood flowing inthe azygos vein away from the ablation zone. For example, a deployableocclusive structure may be a balloon such as a urethane balloon having alength (along the axis of the shaft) of about 2.5 mm and an inflateddiameter of about 2.5 mm to 7 mm (e.g., 3 mm to 6 mm, 4 mm to 5 mm). Theballoon may be in fluid communication with an inflation port connectingthe balloon with an inflation lumen connectable to an inflation sourceon the proximal end of the catheter. Optionally, the inflation lumen maybe in fluid communication with an irrigation lumen connectable to anirrigation source and pump. Optionally such a catheter may have aballoon with holes that allow irrigation fluid to exit the inflatedballoon and flow toward the ablation element(s).

Ablation catheters may have a proximal radiopaque marker positioned onthe shaft at or proximal to the proximal end of the ablation element(s).Optionally, ablation catheters may include a distal radiopaque markerwhich may be positioned on the shaft at or distal to the distal end ofthe ablation element. Optionally, there may be a space between a distalradiopaque marker and the distal end of the ablation element, the spacehaving a length in a range of 0.1 mm to 25 mm, such as 0.1 mm to 5 mm,such as 0.1 mm to 3 mm, such as 0.5 mm, 1 mm, or 1.5 mm. For example, asshown in FIG. 2 a distal radiopaque marker 130 may be aligned with orpositioned relative to an anatomical landmark such as the costovertebraljoint 61 and a space 135 (e.g., 0.1 mm to 25 mm) is between the distalradiopaque marker 130 and the distal end of the ablation element 132ensuring the ablation element is safely distant from the sympathetictrunk 54. Optionally, a deployable structure 134 may be positioned inthe space transitionable between a contracted state (OD similar to theshaft OD e.g., in a range of 1.5 mm to 3 mm) and deployed state (ODincreases to a range of 3 to 7 mm). The deployable structure may be aballoon, bellows, wire mesh, wire braid, coated wire mesh, or coatedwire braid.

An example of an ablation catheter that is sized and adapted for GSNablation is shown in FIG. 2. Ablation catheter 81 has an elongated shaftsized and adapted to reach a T11 intercostal vein from an introductionsite at a femoral vein or jugular vein. The distal section of catheter81, shown positioned in an intercostal vein 55, includes a distalradiopaque marker 130 that is aligned with or positioned relative to acostovertebral joint 61, an ablation element 131 comprising orconsisting of a distal conductive coiled RF electrode 132 and a proximalconductive coiled RF electrode 133, an optional inflatable balloon 134disposed between the ablation element 131 and the distal radiopaqueelectrode 130. The distal radiopaque marker 130 is optionally spaceddistally apart from the distal end of the ablation element 132 by adistance 135 for example in a range of 0 to 25 mm (e.g., such as a rangeof 0.1 mm to 20 mm, such as a range of 0.1 mm to 15 mm, a range of 0.1mm to 3 mm, such as 0.5 mm, 1 mm, or 1.5 mm). Catheter 81 also includesa proximal radiopaque marker 136 that is located at or near a proximaledge of the ablation element 131. In some embodiments proximalradiopaque marker 136 is axially spaced between 0 mm and 25 mm from aproximal end of ablation element 31 (which may be from a proximal end ofablation element 133).

The exemplary axial distances between markers and electrodes describedherein (e.g., 0 mm to 25 mm, or 0 mm to 15 mm) may be integrated intoany other ablation catheter herein unless indicated herein to thecontrary.

Ablation electrodes 132 and 133 (or any other ablation electrode herein)may be made from, for example, Nitinol wire coiled around the cathetershaft, which may allow the electrodes to be flexible so they cantraverse a tight bend from the azygos vein to the intercostal vein andalso create a long ablation (e.g., 5 to 25 mm). Nitinol is an example ofa superelastic material that allows the ablation element(s) to bend whentraversing anatomical bends, and then elastically return to a linear orstraight configuration once the electrode is past the bend.

Any of the distal sections herein may thus be described as a distalsection that has an at-rest (as manufactured) linear or straightconfiguration. This would be in contrast to distal sections that mayrevert or assume non-linear at-rest configurations (e.g., a distalsection with electrodes thereon that returns to a coiled configuration).

Optionally, the ablation catheter 81 includes at least one irrigationport 137 (as shown in FIG. 2) in fluid communication with an irrigationlumen that is near the coil electrodes for delivering a fluid such assaline. Saline delivery may facilitate delivery or removal of thedevice, or can be used during energy delivery to improve ablationformation and prevent overheating, for example. Optionally, catheter 81may include a guidewire lumen 82 for delivery over a guidewire 79.

FIG. 8A illustrates a portion of an exemplary ablation catheter,including at least a portion of a distal section thereof. The ablationcatheter in FIG. 8A includes an ablation element that includes a distalablation element and a proximal ablation element. The ablation element(and other ablation elements herein) includes or consists of a distalconductive coiled RF electrode 132 and a proximal conductive coiled RFelectrode 133, as shown in FIG. 8A. Both distal and proximal coiledelectrodes may be helical coils positioned around and at least partiallyon the outer surface of the shaft, optionally in a groove in the shaft.The coiled electrodes may be helical, and may have varying directions,pitches, or wire thickness, and may be made from a round wire or ribbonwire of electrically conductive material such as stainless steel orsuperelastic Nitinol, optionally electropolished, optionally including aradiopaque material such as platinum iridium. Alternatively, one or morecoiled electrodes may be made from a laser cut tube such as a Nitinoltube forming a coiled pattern or other flexible pattern. Alternatively,the ablation element (e.g., ablation element 131) may be made from adistal and a proximal flexible electrode in the form of wire mesh orbraid. Alternatively, the flexible ablation element may comprise aplurality of ring electrodes each having a length no more than 5 mm,such as 3 mm. Optionally, the flexible ablation element may have anexpandable diameter transitionable from a contracted delivery state toan expanded deployed state (e.g., having an outer diameter up to about 5mm) so it can expand to contact the vessel wall.

Electrodes herein, such as the proximal and distal electrodes herein(e.g., distal electrode 132 and proximal electrode 133) may have alength that is in a range of 4 mm to 12 mm, such as 5 mm to 11 mm, andin some embodiments they are or about 5 mm, 5.5. mm, 6 mm, 6.5 mm, 7.0mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5. mm, 10 mm, 10.5 mm, or 11 mm.Proximal and distal electrodes may have the same or substantially thesame lengths, including lengths that are in the ranges provided herein(e.g., 5 mm to 11 mm). In some embodiments electrodes may have differentlengths. For example, in some examples distal electrode 132 may belonger than proximal electrode 133, but the electrodes individually mayhave any of the lengths herein. In some examples distal electrode 132may be shorter than proximal electrode 133, but the electrodesindividually may have any of the lengths herein.

For catheters that have a plurality of electrodes, each electrode may beconnected to an independent conductor passing through the elongate shaftto the proximal region of the catheter where it is connectable to anextension cable or ablation energy source. This can allow each electrodeto be independently energized in monopolar mode or bipolar mode.

For some catheters with distal and proximal electrodes, the cathetersmay include a gap between a distal end of the proximal electrode and aproximal end of the distal electrode. In some embodiments the gap may bein a range of 0 to 5 mm, such as 0 mm 4 mm, such as 0.1 mm to 1.25 mm,such as 0.25 mm, 0.5 mm, 0.75 mm, 1 mm, or 1.25 mm. Preferably theproximal and distal electrodes are not in electrical communication withone another. Alternatively, the proximal and distal electrodes may atleast partially overlap one another along their lengths, as long as theyare not in electrical communication with one another.

A gap between proximal and distal electrodes may be such that it is notso large that it prevents a continuous ablation lesion to be formed.Gaps described herein (e.g., 0 mm to 5 mm, such as 0.1 mm to 1.25 mm,such as 0.25 mm, 0.5 mm, 0.75 mm, 1 mm, or 1.25 mm) can provide theexemplary benefit of providing for continuous lesion formation.

Ablation catheters herein may include one or more temperature sensors.FIG. 8A illustrates an exemplary ablation catheter that comprises atleast one temperature sensor. The ablation catheter shown includes, forexample, a proximal temperature sensor 139 that may be positioned incontact with proximal electrode 133, and optionally on the proximal endof proximal electrode 133. The ablation catheter shown also includes adistal temperature sensor 140 that may be positioned in contact withdistal electrode 132, and optionally on the distal end of the distalelectrode. Any of the ablation catheters herein may optionally includeanother temperature sensor that may be positioned between proximal anddistal electrodes, or between a plurality of electrodes. For cathetersthat include one or more temperature sensors, the temperature sensor(s)may be thermocouples (e.g., T-type) or thermistors. Optionally, at leastone temperature sensor may radially extend or be radially extendablefrom the catheter shaft to contact tissue up to 3 mm away from thecatheter surface. The temperature sensor(s) may be connectable at theproximal region of the catheter to a computerized energy deliveryconsole where signals from the sensors may be input and used in anenergy delivery control algorithm.

Any of the ablation catheters herein may include one or more irrigationports (which may be referred to herein as holes or apertures) in fluidcommunication with an irrigation lumen that is connectable to a fluidsource at the proximal region of the catheter for delivering a fluidsuch as saline (e.g., normal or hypertonic saline) to the vessel. Theports may be formed in one or more layers of the elongate shaft tocreate the fluid communication between the port and the irrigationlumen. The fluid may function to cool or remove heat from theelectrode(s) and/or vessel wall, to flush blood from the vessel toreduce risk of clot formation or improve ablation consistency, toconduct electrical energy from the ablation electrodes, to controlpressure in the vessel, to facilitate delivery of the distal section ofthe ablation catheter to a target vessel (e.g., intercostal vein), or tofacilitate removal of the distal section of the ablation catheter fromthe target vessel. Optionally, one or more irrigation ports may bedistal to the ablation element(s), or distal to each of the plurality offlexible ablation elements. In some embodiments, any of the irrigationport(s) may be positioned radially under the flexible ablationelement(s). In some embodiments, one or all irrigation ports may bedisposed between windings of coiled ablation element, such that the portis not radially under the winding of the ablation element. Optionally,an irrigation port may be positioned in an axial gap or space betweenadjacent ablation electrodes. Optionally, one or more irrigation portsmay be in a cavity of a deployable occlusive structure (e.g., balloon)and may function to inflate the balloon, wherein the balloon may have aperforation on its proximal side that allows the fluid to escape theballoon into the target region of the vessel.

FIGS. 8A-10 illustrate distal sections of ablation catheters thatinclude a plurality of irrigation ports between windings of coiledablation elements (although only one port 137 is labeled, the others canbe seen in the figures). In the side views shown in FIGS. 8A, 8B, 9 and10, the exemplary ports are linearly aligned, parallel to a long axis ofthe distal section. Additionally shown in the side views of FIGS. 8A,8B, 9 and 10, there is an irrigation port between every adjacent pair ofwinding material (even though coiled elements 132 and 133 are eachformed by a continuous winding along their lengths). The central port137 axially between the ablation elements may or may not be included. Inany of the embodiments, every port in the distal section may be betweena winding (in the side view). Alternatively stated, in any of theembodiments, none of the ports may be radially under a winding structureof the ablation element.

Optionally, as shown in FIG. 8D, irrigation holes (which may be referredto herein as apertures or ports) 137 may be positioned between windingsof the coil electrodes and be circumferentially distributed to depositsaline along the length of the ablation electrodes as well ascircumferentially around the electrodes. In FIG. 8D the irrigation holes137 follow a helical path, optionally of the same pitch as the coilelectrode with equal spacing between holes as shown in FIG. 8D. Asshown, even though the example in FIG. 8D does not include a centralport between electrodes (as do the examples in FIGS. 8A and 8B), theirrigation holes may still be considered to have or follow a helicalpath. That is, there may be a greater spacing between sections ofhelical ports than between adjacent ports in the sections. The exampleshown in FIG. 8D may, however, also include a central irrigation portbetween electrodes (as in the examples of FIGS. 8A and 8B).

The irrigation holes may be created (e.g., laser drilled) in the tube(or tubular member) prior to or after positioning or connecting theelectrode coil(s) to the tube. Optionally, size and quantity ofirrigation holes are chosen along with an irrigation flow rate range tomaintain a back pressure in the irrigation lumen so that irrigatedsaline jets from the irrigation holes, which may evenly, consistentlyand predictably fill the vessel (e.g., intercostal vein) with saline.For example, an ablation catheter may be adapted to accept a saline flowrate in a range of 30 to 50 mL/min during ablation and may haveirrigation holes with a diameter of 0.003″ and a quantity of 34 holes oralternatively holes with a diameter of 0.009″ and a quantity of 17holes.

Optionally, there may be more holes associated with the distal electrodethan the proximal electrode, or vice versa. Optionally, one or moreirrigation holes may be positioned distal to the distal electrode, forexample within 3 mm distal of the distal electrode. This may improvecooling of the distal electrode including a temperature sensor incommunication with the distal electrode, in particular if thetemperature sensor is located at the distal end of the distal electrode.For example, as shown in FIG. 8E, a schematic illustration of a distalportion of an ablation catheter, irrigation holes 137 may be arranged ina helical pattern between at least some windings of a proximal helicalelectrode 133 and likewise irrigation holes 137 may be arranged in ahelical pattern between at least some windings of a distal helicalelectrode 132, and a plurality of irrigation holes 461 may be arrangeddistal to the distal electrode and a plurality of irrigation holes 460between the proximal and distal electrodes. In this example, theirrigation holes 137 that are between windings of the coiled proximal133 and distal 132 electrodes follow a helical path around the shaft 340having the same pitch as the helical coil electrodes or at leastsufficiently the same pitch such that the holes 137 remain between thewindings of the coiled electrodes. Furthermore, the holes 137 may bespaced apart from one another along the helical pathway in regularintervals, for example every 96 degrees (or a regular interval in arange of 4 to 110 degrees), which may provide an even circumferentialdistribution of irrigation. The pitch of the coiled electrodes may gettighter at one or both ends of each coil. For example, each end of eachcoil may wrap around the shaft 340 and contact the adjacent turn of thecoil making a closed loop at each end of the coil, where the connectionsare soldered together. This may help to hold the coil securely to theshaft and contain the ends to avoid a risk of a loose wire end gettingcaught on tissue or the delivery sheath. The same solder joint mayinclude an RF conductor and optionally thermocouple wires forming athermocouple junction as shown as distal thermocouple junction 140,which is shown at the distal end of the distal electrode 132, andproximal thermocouple junction 139, which is shown at the proximal endof the proximal electrode 133. Due to the decreased coil pitch at theends of the coils, there is less room to place irrigation holes.Optionally, irrigation holes may be positioned only in central regionsof the coiled electrodes and not where the pitch decreases at the ends,for example within the beginning or ending 3 turns. To compensate forreduced irrigation at the ends of the coiled electrodes when holes arenot placed in the last few turns, irrigation holes 461 may be positioneddistal to the distal electrode 132, and irrigation holes 460 may bepositioned between the proximal 133 and distal 132 electrodes. Forexample, a quantity of distal holes 461 in a range of 1 to 5 (e.g., 3)may be circumferentially evenly spaced (e.g., radially symmetric) andwithin a distance 462 (e.g., in a range of 0.1 to 3 mm, in a range of0.1 to 1 mm) of the distal end of the distal electrode 132. Similarly,for example, a quantity of holes 460 between the electrodes in a rangeof 1 to 5 (e.g., 3) may be circumferentially evenly spaced (e.g.,radially symmetric) and within a space 463 (e.g., in a range of 0.5 to1.0 mm) between the distal electrode 132 and proximal electrode. Sinceblood flows from distal to proximal in the intercostal vein, irrigatedsaline flowing out of distal holes 461 would sufficiently bathe and coolthe distal few turns of the electrode 132; the proximal few turns of thedistal electrode would be bathed and cooled by saline flowing from holesbetween windings as well as from the distal holes 461; likewise thedistal few turns of the proximal electrode 133 would be cooled andbathed by the holes 460 between the electrodes; and the proximal fewturns of the proximal electrode would be bathed and cooled by salineflowing from holes between windings as well as from the holes 460 andfrom other holes 137 and 462 associated with the distal electrode. Inone exemplary embodiment as shown in FIG. 8E the catheter has threecircumferentially evenly spaced distal irrigation holes 461, threecircumferentially evenly spaced irrigation holes 460 between theproximal and distal electrodes, 15 helically evenly spaced irrigationholes 137 between windings in the distal electrode, and 15 helicallyevenly spaced irrigation holes 137 between windings in the proximalelectrode, totaling 36 irrigation holes, each having a diameter of0.003″.

Alternatively, in any of the examples herein, irrigation holes may bepositioned under the coil electrode windings as well as between thewindings.

Alternatively, any of the devices herein may include a section of tubethat the electrodes are positioned over that may be a porous tube madefrom a material that is inherently porous, for example a mesh or woventube.

Alternatively, any of the coiled electrodes herein may have a flatprofile such as a ribbon of conductive material wrapped helically arounda tube. A flat profile compared to a round wire profile may in somesituations be easier to deliver or remove from a tight vessel. FIG. 21Ashows an exemplary distal portion of an ablation catheter having anablation element 385 having a plurality of coiled electrodes (a firstelectrode 386 and a second coiled electrode 387 in this example) madefrom flat ribbon wrapped helically around a tubular shaft 388. The flatribbon may be a conductive material, optionally a superelastic Nitinolribbon shape set into a helical coil having, for example only, an innerdiameter of 0.069″+/−0.004″ and a pitch of about 0.047″. SuperelasticNitinol may have a benefit of kink resistance and elastically returningto a preset shape during or after being deformed when delivering thedevice to a target vessel. However, alternative materials such asstainless steel or a conductive alloy could be used. Optionally, atleast a portion of the ribbon electrode may be made with a radiopaquematerial such as platinum iridium. Optionally, the surface of the ribbonelectrode may be etched and passivated. The flat ribbon may have athickness in a range of, for example only, 0.002″ to 0.003″ and a width389 in a range of 0.010″ to 0.020″. The length 390 of each coil may beabout 8 mm+/−0.5 mm. The flat ribbon electrodes may be applied to beflush with the surface of the tubular shaft. For example, the tubularshaft may be indented where the flat ribbon connects with the shaft orthe tubular shaft may re-molded or softened during application of theflat ribbon to allow it to sink into the shaft. Alternatively, the flatribbon electrodes may extend beyond the surface of the shaft, forexample by the thickness of the ribbon, which may be in a range of0.002″ to 0.003″. Optionally, the edges 391 of the ribbon electrode, forexample on the outer diameter, may be rounded, chamfered or tapered,which may further facilitate delivery or removal of the catheter intothe target vessel or may reduce high current density during delivery ofRF energy. Irrigation ports 137 may be positioned between the windingsof the flat ribbon electrodes as shown in FIG. 21A, or in otherconfigurations disclosed herein. Another alternative form of a flathelical electrode, as shown in FIG. 21B, may include an assembly madefrom a conductive material 396 such as superelastic Nitinol, stainlesssteel or an alloy, on a non-conductive substrate 397 (e.g., a flexcircuit), which may facilitate manufacturing. The non-conductivesubstrate 397 may be for example, polyimide, and the conductive trace396 may be connected to the substrate with adhesive. The assembly mayhave a wire strain relief 398 in the substrate, through which conductorsmay pass from a lumen in the catheter shaft to a wire solder pad 399that is in electrical communication with the conductive material 396.Optionally, temperature sensors 139, 140, such as thermocouples, may bepositioned on the wire solder pad along with conductors supplying RF tothe electrodes. The assembly may have a thickness in a range of 0.002″to 0.003″, with a conductor thickness in a range of 0.0015″ to 0.0025″.The width of each trace may be in a range of 0.010″ to 0.020″.

Optionally, the ablation catheter may have a deployable elementtransitionable from a contracted delivery state (e.g., having an OD in arange of 1.5 mm to 3 mm) to an expanded deployed state (e.g., having anOD in a range of 2.5 mm to 6 mm) that functions to one or more of anchorthe distal section of the catheter in the target region of the vessel,to occlude blood flow, to contain delivered fluid such as saline, tomaintain vessel patency, or to act as an electrical insulator. Forexample, as shown in FIG. 8B, any catheter herein may also include adistal deployable element 134 coupled with optimized irrigation flowthat may create a virtual electrode that provides an effective ablationwithout the need for wall contact. Distal deployable element 134 may bea balloon (e.g., compliant balloon) as shown in FIG. 8B, oralternatively a bellows or coated stent or mesh. Distal deployableelement 134 is distal to the ablation element, which may includeproximal and distal electrodes as shown in FIG. 8B.

Optionally, any of the ablation catheters herein may have a proximaldeployable element. FIG. 9 illustrates an exemplary ablation catheterthat includes proximal deployable element 141 that can be contracted tohave an OD in a range of 1.5 to 3 mm in a delivery state, and bedeployed to have an OD in a range of 4 to 10 mm in a deployed state asshown in FIG. 9. The proximal deployable element 141 may function to oneor more of anchor the distal section of the catheter in the targetregion of the vessel, to occlude blood flow, to contain delivered fluidsuch as saline, to act as an electrical insulator, to maintain vesselpatency, to act as a depth stopper (e.g., having a deployed OD largerthan the targeted intercostal vein) to prevent the distal section frombeing advanced too far into the intercostal vein, or to direct bloodflow in the azygos vein away from the ostium to facilitate ablation nearthe ostium. A proximal deployable element and a distal deployableelement coupled with optimized irrigation flow may create a virtualelectrode that provides an effective ablation without the need for wallcontact. A proximal deployable element may be a balloon (e.g., compliantballoon) as shown in FIG. 9, or alternatively a bellows or coated stentor mesh. Any of the catheters herein may include a proximal deployableelement and a distal deployable element.

Optionally, any of the ablation catheters herein may include a middle orcentral deployable element. FIG. 10 illustrates an exemplary ablationcatheter that includes a middle deployable element 142 that can becontracted to have an OD in a range of 1.5 to 3 mm in a delivery state,and be deployed to an expanded state (e.g., having an OD in a range of2.5 mm to 6 mm) as shown in FIG. 10. The middle deployable element mayfunction to one or more of anchor the distal section in the targetregion of the vessel, to occlude blood flow, to contain delivered fluidsuch as saline, to maintain vessel patency, or to act as an electricalinsulator. A middle deployable element may be used to isolate the vesselbetween a distal deployable element and the middle deployable elementand around the distal ablation element to create a virtual electrodethat provides an effective ablation without the need for wall contact.Likewise, the section of vessel between the middle deployable elementand a proximal deployable element may be isolated. The middle deployableelement may be a balloon (e.g., compliant balloon) as shown in FIG. 10,or alternatively a bellows or coated stent or mesh. In an embodimentwherein the ablation energy is electroporation, the middle deployableelement may function as an electrical insulator to direct electricalcurrent out of the vessel in through tissue around the vessel to moreeffectively ablate the target nerve. In alternative embodiments, anablation catheter may have a middle deployable element and only a distaldeployable element (i.e., no proximal deployable element) or only aproximal deployable element (i.e., no distal deployable element).

The disclosure above described exemplary methods of positioning anablation catheter within an intercostal vein to ablate a GSN whileminimizing or avoiding damage to non-target structures. The ablationcatheters above, including those shown in FIGS. 8A, 8B, 9, and 10,included one or more radiopaque markers (e.g., distal marker 130 andproximal marker 136) that can be used as part of those methods ofpositioning. While the ablation catheters in FIGS. 8A, 8B, 9 and 10 areexamples of ablation catheters that can be used when performing themethods herein, it is understood that the methods can be performed witha variety of ablation catheters. It is thus understood that the methodsherein are not limited by the particular ablation catheters herein. Itis also understood that the ablation catheters herein need not be usedwith the positioning methods herein.

Alternative embodiments of TSN/GSN ablation catheters may have one ormore the features that are described herein, such as proximal and distalradiopaque markers spaced as described, irrigation lumens(s),temperature sensor(s), guide wire lumens, flexible shaft section, andmay also include alternative ablation elements. For example, ablationelements may be RF electrodes having different configurations orablation elements that deliver a different type of ablation energy suchas ultrasound, electroporation, cryoablation, laser, chemical or otherablation modality. Ablation catheter features that are described withrespect to one embodiment or example herein may be incorporated intoother suitable embodiments unless the disclosure indicates otherwise.Features with the same or similar reference numbers are understood to beoptionally included and can be the same component.

For example, FIG. 11 illustrates a distal section of an ablationcatheter. The ablation catheter includes an ablation element that may bean RF electrode that includes a plurality of wire struts 143 running thelength of the ablation element and arranged around the circumference ofthe shaft. The wire struts are electrically conductive, for example madefrom stainless steel, Nitinol or the like, and transitionable from acontracted delivery state (e.g., having an OD in a range of 1.5 to 3 mm)to an expanded deployed state (e.g., having an OD in a range of 2.5 mmto 6 mm) to contact the vessel wall, in particular an intercostal vein.The wire struts may be deployed by applying tension to a pull wire thatmoves a collar holding or otherwise secured to one end of the wirestruts, shortening the distance between the two ends, which causes thewire struts to bend outward. The struts may be heat set in a biasedconfiguration, such as those shown in FIG. 11. Optionally, an RFelectrode may have multiple (e.g., two) RF electrodes made of wirestruts, wherein the multiple electrodes are positioned next to oneanother similar to the coiled electrodes shown in FIGS. 8 to 10.Optionally, the wire struts may be made from a laser cut tube.Optionally the distal end, proximal end or both ends of the expandablewire electrode may have a membrane that functions to occlude the vesselwhen expanded and function similar to the deployable structures (e.g.,balloons) shown in FIGS. 8A to 10.

FIG. 12 illustrates an exemplary ablation catheter with ablationelement(s) carried by an expandable balloon. FIG. 12 illustrates adistal section of an ablation catheter with an RF ablation element,wherein the ablation element includes one or more electricallyconductive element(s) positioned on expandable balloon 144. Theconductive elements may be a film or conductive ink or flexiblecircuits. Sensors (e.g., temperature sensors) may be positioned on theballoon as well. Optionally the balloon may be inflated by deliveringfluid such as saline or air into the balloon. Optionally, the conductiveelement(s) or the balloon may have perforations allowing fluid to passthrough to cool the electrode or conduct energy. The pattern of theconductive element(s) may be cylindrical 148 (FIG. 12), helical 149(FIG. 13A), a plurality of electrodes each having a helicalconfiguration 150 (FIG. 13B), electrodes with a wavy (e.g., sine wave)or zig-zag pattern 151 (FIG. 14), or other pattern adapted tocircumferentially ablate around a vessel. The examples shown in FIGS. 12to 14 include optional distal and proximal radiopaque markers that canbe used with any of the methods of positioning described above.

FIG. 15 illustrates an additional exemplary distal section of anablation catheter that includes an electrically conductive elementwithin a membrane. The catheter in FIG. 15 includes an RF ablationelement that is an electrically conductive wire 145 (e.g., wire coil) onor around the catheter shaft within a cavity defined by a membrane 185.The membrane may be an ionomer, a conductive membrane, or a weepingmembrane. The optional distal and proximal markers are shown distal andproximal to the balloon, respectively.

FIG. 16 illustrates an example of a distal section of an ablationcatheter, which can may be used with the methods of positioning herein.Another embodiment of an RF ablation element is shown in FIG. 16 whereinthe ablation elements are a plurality of shorter RF electrodes 146 on atapered shaft 147. This embodiment is different in that the total lengthof the shaft carrying ablation elements may be longer than previouslydescribed as 5 mm to 25 mm (preferably 10 mm to 15 mm). Instead, thecatheter includes multiple sections (e.g., two or three) that each havea length in this range, but are selectively chosen to deliver ablationenergy depending on how they fit in the intercostal vein. The taperedshaft may function to fit a range of intercostal veins (e.g., in a rangeof 2.5 mm to 5 mm). The distal end is narrower than the proximal end andthe electrodes may be independently and selectively energized. If thedistal section of the catheter is delivered to a relatively narrowintercostal vein, for example having an inner diameter of about 2.5 mm,the distal narrow portion may be advanced into the vein and selected forenergy delivery, while the proximal larger portion may remain in theazygos vein and not used to delivery ablation energy. If the intercostalvein is larger, for example 5 mm inner diameter, the distal section maybe advanced further into the intercostal vein until the largerelectrodes are wedged into the vessel contacting the wall. The largerproximal electrodes may be selected for energy delivery while the distalelectrodes are inactive to avoid injury to the sympathetic trunk.Optionally and intermediate section of electrodes may be sized to fit anintercostal vein having an inner diameter of about 3.5 mm. The pluralityof electrodes may be coiled wire, laser cut tube, or solid electrodes.The electrodes may be radiopaque or have radiopaque markers associatedwith them so the user can image where the electrodes are positioned inthe intercostal vein and choose which section of electrodes to activate.

Another embodiment of a transvascular ablation catheter 241 for ablatinga TSN or GSN from within an intercostal nerve is shown in FIG. 17A. Thecatheter 241 may extend along a longitudinal axis. An expandable member,for example in the form of a balloon 242 having an unexpanded state andan expanded state, may be coupled to a distal section 243 of thecatheter. The expandable member (e.g., balloon) may have acircumferential treatment zone 248 (e.g., having a length in a range of5 to 25 mm, in a range of 10 to 15 mm) extending along the longitudinalaxis in the expanded state and surrounding the vessel 55. The catheterincludes an electrode assembly 252, which comprises a plurality ofelectrode pads 244, may be mounted or otherwise secured to the balloon242. Each electrode pad assembly may include a substrate supportingfirst and second electrode pads with each electrode pad having a pair ofelongate bipolar electrodes and connected with an electrical trace 249.The electrode pads of each electrode pad assembly may be longitudinallyand circumferentially offset from one another. The method may alsoinclude expanding the balloon in the intercostal vein so as toelectrically couple the electrodes with a wall of the intercostal veinand driving bipolar energy between the electrodes of each bipolar pairso as to therapeutically alter the TSN or GSN within 5 mm of theintercostal vein such that the blood volume of the patient isredistributed for treatment of diseases such as pulmonary hypertension,or heart failure (e.g., HFpEF).

Each electrode pad may include a temperature sensor disposed between theelectrodes of the pair. The expanding of the balloon may couple thetemperature sensors with the wall of the intercostal vein. In someembodiments, the method may further include directing the energy to thebipolar pairs in response to a temperature signal from the temperaturesensor so as to heat the wall approximately evenly.

To create an ablation having a depth of 5 mm to target a GSN from anintercostal vein the electrode pads may be cooled to allow greater powerto be delivered without desiccating tissue of the vein wall, whichimpedes ablation depth. The electrodes may be cooled for example, bycirculating coolant in the balloon 242. In one embodiment coolant may beinjected into the balloon 242 from a coolant injection port 246 at oneend of the balloon chamber and the coolant may exit the chamber throughan exit port 247 at the opposing end of the chamber and allowed toreturn through the catheter through an exit lumen.

In another embodiment coolant may be deposited into the blood streaminstead of returning through a lumen in the catheter. This embodimentmay allow a thinner, more flexible catheter shaft or a larger coolantdelivery lumen to increase flow rate of the coolant. A coolant exit portmay be smaller than the coolant injection port to allow pressure toincrease in the balloon to inflate it. The coolant exit port may be incommunication with a lumen that does not pass through the full cathetershaft to the proximal end but instead passes to the distal end of thecatheter to deposit the coolant (e.g., normal saline) into theintercostal vein. Optionally the coolant exit lumen may be the samelumen as a guidewire delivery lumen.

Electrode pads may be positioned around the balloon to make acircumferential ablation pattern that is as long as the target ablationzone 58 (e.g., up to 20 mm, about 15 mm, between 12 and 18 mm). Forexample, as shown in FIG. 17B, a balloon with electrode pads mounted toan elongate shaft 253 may have an undeployed state having a diameter ofabout 1 mm to 2.5 mm and a circumference of about 3.14 mm to 7.85 mm andbe expandable to a deployed state having a diameter in a range of about3 mm to 5 mm and a circumference in a range of about 9.4 mm to 15.7 mm.Electrode pads 244 may be separated or spaced by a distance 250 of lessthan 5 mm (e.g., less than 2.5 mm) and width or arc length 251 in arange of 3 mm to 3.5 mm. Electrode pads 244 may have a length of about 3to 5 mm each. As shown in FIG. 17A, an electrode pad assembly 252 maycomprise multiple electrode pads 244 arranged on four separate rowsconnected together by electrical traces 249, the rows evenly spacedaround the circumference of the balloon 242 (e.g., four rows at each 90degree quadrant). Longitudinally, the pads 244 on one row may be offsetfrom pads of adjacent rows. When the balloon is in its unexpanded statethe space between the electrode pads is decreased (e.g., to about 0 to 1mm) and the adjacent rows interlock with one another. In its expandedstate the space 250 between the pads expands due to the expandableballoon 242 to about 2 mm to 5 mm. The balloon 242 may be a compliantmaterial such as latex or a non-compliant material that flexibly foldsto contract.

Alternatively, electrode pads may be positioned only on one side (e.g.,50%, 40%, 30%, 25% of the balloon's circumference) to generate adirectional ablation pattern that is all toward the same side and of alength of the target ablation zone 58. For a directional ablationcatheter, a radiopaque marker may be positioned on the distal section ofthe catheter to indicate radial direction. For example, a radiopaquemarker may be asymmetric and positioned on the same side or opposingside as the directional electrode pads to indicate and in use aphysician may torque the catheter to aim the radiopaque marker and thusthe electrode pads away from the vertebra, which is always toward theGSN. FIG. 17A shows several small electrode pads. Alternatively, thedevice may have larger and fewer electrode pads, for example two orthree directional electrode pads (e.g., 3 to 5 mm long) on the same sideof the balloon that span the target ablation zone 58. A gap (e.g., 1 to3 mm) between electrode pads may facilitate bending of the device totraverse from the azygos vein to the intercostal vein. The ablationcatheter in FIGS. 17A and 17B can include proximal and/or distalradiopaque markers, and may be used with methods of positioningdescribed herein.

Just proximal to the balloon the catheter shaft may comprise a flexibleneck 245 that allows the ablation balloon to sit in the intercostalvein's natural orientation. Given the small bend radius at this locationa stiff shaft could apply force to the ablation balloon causing it todistort the intercostal vein and reduce predictability of ablation zone.A flexible neck may be made of a softer durometer polymer (e.g., Pebax®)and may have a wire coil embedded in the material, which may allowflexible bending while providing pushability. This type of flexible neckmay be incorporated into other ablation catheters herein.

The electrode(s) that are most proximal may be placed just in theintercostal vein near the ostium. Blood flow through the azygos vein maymetabolically cool tissue near it impeding ablation creation. A largeramount of ablation power (e.g., RF) or longer duration may be deliveredto this proximal electrode(s) than the rest of the electrode(s) tocompensate for the blood flow cooling.

The catheter 241 may have a distal radiopaque marker 255 positioneddistal to the ablation elements, for example distal to the balloon 242,and/or a proximal radiopaque marker 254 positioned proximal to theablation elements 244, for example proximal to the balloon 242. Thedistal and proximal radiopaque markers 255, 254 may be separated alongthe longitudinal axis of the shaft by a distance in a range of 5 mm to25 mm (e.g., 10 mm to 15 mm). Any other features or description ofradiopaque markers herein may apply to markers 255 and/or 254.

FIG. 18A illustrates an exemplary ultrasound ablation catheter. Catheter220 includes an elongate shaft 225 with a proximal region and a distalsection and an ablation assembly 232 mounted to or at the distalsection. The ultrasound ablation catheter 220 has an inflatable balloon221 which may have a geometry suitable for expansion in an intercostalvein (e.g., outer diameter 222 in a range of 2.5 to 5 mm in its inflatedstate) and a length 223 in a range of 8 to 30 mm. Within the balloon221, multiple ultrasound transducers 224 are positioned on a shaft 233centered in the balloon 221. The transducers 224 may be placed seriallyspanning a length 226 that is in a range of 5 to 25 mm to generate anablation of a similar length capable of creating an ablation the lengthof the target ablation zone 58. Due to the small diameter of theintercostal vein the reduced balloon size may risk contacting thetransducer or getting over heated by the transducer, which may rupturethe balloon or reduce efficacy of the ablation. To remedy this riskstruts or protrusions 227 may be positioned between the transducer andballoon. The struts 227 may be for example polymer strands elasticallypre-shaped to radially expand away from the transducers 224. To make alonger ablation to span the targeted ablation zone, multiple transducersmay be incorporated (e.g., three 4 mm long transducers) and spaced apartwith flexible gaps 228 between them to facilitate traversing the smallbend radius from the azygos vein to intercostal vein. For example, shaft225 may be a braid reinforced polyimide tube with an optional guidewirelumen 229 for delivery over a guidewire 79 and carry electricalconductors that energize the transducers 224. The ultrasound transducers224 may be cylindrical for producing circumferential ablation around thetarget vein. Alternatively, the ultrasound transducers may be flat orhemicylindrical to produce an ablation that is a partial segment of thecircumference of the vein and a radially identifiable radiopaque marker230 may be positioned on the distal section allowing a user to orientthe direction of ablation toward the patient's anterior where the GSNpasses over the vein 55. Optionally, the ultrasound transducer may beconfigured to image as well as ablate and the imaging function may beused to assess nearby structures such as the lung, vertebra, ribs.Imaging ultrasound may be used to confirm the transducer is aimingtoward the lung, which is the direction of the target GSN. Optionally,the shaft may have a flexible neck 231 within 10 mm proximal of theballoon 221 to allow the distal section to sit well in the intercostalvein.

In an alternative embodiment of an ultrasound ablation catheter, thecatheter can be composed of an active ultrasound transducer and aninflatable reflector balloon, which may be on the same catheter oralternatively be on separate catheters. The reflector balloon may havean inflated diameter in a range of 2.5 to 4 mm and on its proximalsurface have a shape such as a concave curvature that focuses reflectedwaves on to the target ablation zone. The reflector balloon is locateddistal to the transducer and is inserted in the narrower intercostalvein, while the ultrasound transducer remains in the larger azygos vein.The ultrasound transducer may be exposed to blood flow in the azygosvein or alternatively may be contained in a chamber in an inflatableballoon filled with coolant (e.g., circulating coolant such as sterilewater or saline). The ultrasound energy is directed toward the distalreflector balloon and reflected and focused into tissue surrounding thesplanchnic nerve. The advantage of this approach is that an activeultrasound transducer can be made larger and is not required to gothrough the sharp turn from azygos to intercostal vein. A secondadvantage is that several intercostal veins can be used to targetablation with the same catheter.

The catheter 220 may have a distal radiopaque marker 230 positioneddistal to the ablation elements, for example distal to the balloon 221and a proximal radiopaque marker positioned proximal to the ablationelements, for example proximal to the balloon. The distal and proximalradiopaque markers may be separated along the longitudinal axis of theshaft by a distance in a range of 5 mm to 25 mm (e.g., 10 mm to 15 mm).

FIGS. 8A to 10 illustrate exemplary ablation catheters. The ablationcatheters in these examples includes an ablation element that includesfirst and second flexible coiled ablation electrodes that are axiallyspaced. It may be beneficial to have first and second electrodes ratherthan a single longer electrode to avoid a tendency of the single longerelectrode to heat tissue mostly towards one end of the electrode. Havingmore than one electrode thus can help to create a long and consistentablation in tissue. FIGS. 8A to 10 are thus examples of ablationcatheters that can more consistently create a continuous ablation of thedesired length, such as 10 mm to 25 mm, such as 15 mm to 25 mm, such as15 mm to 20 mm.

An additional exemplary benefit of having first and second electrodesversus a single longer electrode is that only a single relativelyshorter electrode may be energized rather than a single longerelectrodes. This can be advantageous when the patient's anatomy requiresor may benefit from making shorter ablations, such as if the azygos isright centered. In these cases, a longer single electrode may make itdifficult or dangerous to safely ablate tissue while avoiding non-targetstructures. This is described in more detail elsewhere herein.

Additionally, FIGS. 8A to 10 illustrate ablation catheters that havefirst and second ablation elements axially separated by a gap orspacing. This gap is small enough (i.e., not too large) such that acontinuous lesion is formed when energizing the first and secondablation elements, yet is large enough to avoid short circuiting.

Design features of distal sections of ablation catheters herein (e.g.,FIGS. 8A to 10) thus provide exemplary benefits that allow the distalsection to be advanced into position in an intercostal vein and reliablycreate a continuous ablation of at least 10 mm to 25 mm in length, whileallowing shorter ablation sections if needed based on the patient'sanatomy.

In some methods of use, the ablation energy is RF, and an energydelivery controller is adapted to deliver RF power in a range of 15 W to50 W. In some embodiments, the controller is adapted to deliver RF powerin a range of 15 W to 40 W, in a range of 15 W to 35 W, or in a range of20 W to 35 W, such as about 25 W, about 30 W or about 35 W.

In some methods of use, energy is delivered over a period of timebetween 25 seconds and 120 seconds. For example, energy may be deliveredfor 90 seconds, for 100 seconds, for 110 second, or for 120 seconds,wherein for a portion (e.g., half) of the period of time energy, may bedelivered to a first electrode and for the remainder (e.g., half) of theperiod energy may be delivered to a second electrode.

In some methods of use, an irrigation flow rate is from 10 mL/min to 50mL/min, (e.g., 10 mL/min, 15 mL/min, 20 mL/min) during ablation.Optionally, flow rate may be changed automatically by the controlalgorithm in response to changes in measured temperature, impedance orphase. With devices and methods disclosed herein, the TSN may be ablatedin a relatively safe manner, with minimal or reduced adverse effects(such as damage to the lungs or other nerves). Some method of useembodiments herein may temporarily occlude blood flow and reduce aneffect of vein collapse, thus advantageously avoiding challenges of achanging thermal and electrical environment during the heating process.Some method of use embodiments herein may ablate a nerve up to 5 mm fromthe target vessel. Some of the devices herein are dimensioned andconfigured for delivery and positioning in vasculature specified forablating a target nerve (e.g., TSN, GSN).

Some of the devices herein may have one or more features that providesfor a safe delivery to the target vessel.

Some of the devices and methods of use herein may safely deliver energywith temperature monitored energy delivery.

Some of the methods of use herein may generate a lesion capable oftargeting a nerve up to 5 mm away from the target vessel and within atarget region having a continuous lesion length from 5 mm to 25 mm, suchas 10 mm to 25 mm, such as 15 mm to 20 mm, (e.g., 15 mm, 16 mm, 17 mm,18 mm, 19 mm, 20 mm), with a single positioning and delivery of energy.

Some of the devices and methods herein are adapted to avoid risks ofboiling, hot spots, or erratic energy delivery that could decreaseablation efficacy. Furthermore, some embodiments may include nervestimulation to identify a target nerve or non-target nerve to confirmpositioning prior to ablation, or to confirm technical success during orfollowing ablation.

It may be preferred, but not required, that the methods of ablationcreate a continuous ablation zone (i.e., not having separate, discreteregions of ablated tissue that are not connected to each other). Thisensures that the region of tissue where the target GSN nerve or GSNnerve root is likely to be located is most likely to be effectivelyablated by the ablation energy. The continuous ablation zone may becircumferential, or less than circumferential.

Optionally, an ablation confirmation test can then be performed, forexample, by delivering a nerve stimulation signal. Monitoring can beperformed for a physiological response (e.g., splanchnicvasoconstriction, increased heart rate, increased blood pressure) to theablation confirmation test. If the physiological response demonstratesthat the first lesion did not provide a clinically significant amount ofGSN blocking (e.g., by observing a lack of physiological response) thenablation energy can be delivered from the ablation catheter to create asecond lesion in tissue up to 5 mm from the second intercostal vein. Thedistal section of the ablation catheter can be moved to a thirdintercostal vein that is superior to (e.g., superior and adjacent to)the second intercostal vein. The same or different ablation confirmationtest can be performed, followed by another monitoring test. If thephysiological response demonstrates that the first lesion and secondlesion did not provide a clinically significant amount of GSN blocking(e.g., by observing a lack of physiological response) then ablationenergy can be delivered from the ablation catheter to create a thirdlesion in tissue up to 5 mm from the third intercostal vein. Any of theablation confirmation tests may comprise delivering a nerve stimulationsignal from a stimulation electrode positioned on the distal section ofthe ablation catheter configured to generate an action potential in thethoracic splanchnic nerve. Alternatively or in addition to, the ablationconfirmation test may comprise a leg raise test. Alternatively or inaddition to, the ablation confirmation test may comprise adding fluidvolume to the venous system. Alternatively or in addition to, theablation confirmation test may comprise a hand-grip test. Alternativelyor in addition to, the ablation confirmation test may comprise measuringvenous compliance or capacitance.

In exemplary methods in which an ablation confirmation test includes aleg raise test, the method may comprise any of the following steps.Prior to ablation in the lowest intercostal vein, a baseline measurementmay be obtained by raising the legs and measuring the change in centralvenous pressure and waiting for equilibration, that is a measure of thetotal venous compliance including the central veins and splanchnic bed.The legs can then be lowered, to allow equilibration so bloodredistributes back to the legs. An ablation in the lowest intercostalvein (e.g. T11) can then be performed as set forth herein. The legs canthen be raised, followed by waiting for equilibration and re-measurecentral venous pressure. A measurement can then be made to determine ifthere was an appropriate reduction in total venous compliance. If yes,then the GSN has successfully been ablated. If no, then an ablation inthe next higher intercostal vein (e.g., T10) can be performed, as setforth herein. The measurement can be repeated. A determination can thenbe made to see if there was an appropriate reduction in total venouscompliance. If yes, then the GSN has successfully been ablated. If no,then an ablation in the next higher intercostal vein (e.g., T9) can beperformed.

In exemplary methods in which an ablation confirmation test comprises ahand-grip or other activity that increases sympathetic nervous system(SNS) outflow to the splanchnic bed may comprise the following steps. Anablation can be performed in a lowest intercostal vein (e.g., T11).Venous compliance can then be measured. A hand-grip can then beperformed for a predetermined amount of time (e.g., 60 seconds). Venouscompliance can then be remeasured. If there is no change in venouscompliance, the initial ablation was sufficient to achieve a clinicallysignificant outcome. If there still is a decrease in compliance, some ofthe SNS activity caused by the hand-grip is getting through. Theablation in the lowest intercostal vein was thus insufficient to achievea clinically significant effect. An ablation in the next higherintercostal vein (e.g., T10) can then be performed. A hand grip test fora predetermined amount of time (e.g., 60 seconds) can be performed.Venous compliance can then be remeasured. If there is no change incompliance, the second ablation was sufficient. If there is a decreasein compliance, some of the SNS activity caused by the hand-grip isgetting through, and the ablation in the next higher intercostal veinwas thus insufficient to achieve a clinically significant effect.Ablation is the next higher intercostal vein (T9) can then be performed.The procedure is done at this point as ablation at a level higher thanthe 3rd lowest intercostal vein is not anticipated.

Energy Delivery Algorithms

One aspect of the disclosure herein is related to energy deliveryalgorithms that are adapted to be particularly suited for ablatingtissue circumferentially around a narrow blood vessel such as anintercostal vein or other similar vessel to a depth of at least 5 mm andup to 10 mm and from an ablation catheter. The ablation catheter may beany of the catheter embodiments shown in FIGS. 1, 2, 8A, 8B, 8C, 8D, 8E,9, 10, 21A and 21B, wherein the ablation catheter comprises first andsecond electrodes (e.g., two coiled electrodes each having a length in arange of 2.5 to 10 mm, preferably 5 to 8 mm, and an outer diameter in arange of about 1.5 to 3 mm, and a distance between the electrodes in arange of 0 to 5 mm).

A first embodiment of an energy delivery algorithm is referred to as“Multiplexed Monopolar RF”, wherein pulses of RF are delivered to theplurality (e.g., two) electrodes in monopolar configuration withasynchronous waveforms. Each electrode receives a pulsed waveform of RFenergy alternating on and off at a steady frequency. The waveforms maybe for example square wave, sinusoidal, or other form of alternatingwaveform. The on period delivers an ablative level of RF power while theoff period delivers a non-ablative level of RF power (e.g., in a rangeof 0 W to 1 W, about 0.1 W). The waveforms for each electrode areasynchronous, that is to say the waveforms are aligned in time so thatan on period for one electrode is aligned with off periods of theremaining electrode(s) and vice versa. The algorithm has an ablationmode initiated by user activation for example by depressing a button orfoot pedal. The Ablation Mode Algorithm, as shown in FIG. 19, mayinclude parameters that are optionally user defined or may be set bydefault until a user changes them or may be automatically defined. Notethat FIG. 19 is not to scale and the total time, t_(TOTAL) is shortenedfor a simplified illustration of the parameters and concepts. Forexample, if total time is 180 s and both the first and second electrodepulse widths are each 2 s, a true plot would show 45 cycles, howeverfewer cycles are shown for simplicity. The parameters may includeInitial Power, P_(i), First Electrode Pulse Width, PW1, Second ElectrodePulse Width, PW2, Total Therapy Time, t_(TOTAL), Minimum Therapy Time,Lockout Period t_(LO), Secondary Power P₂, and optionally further lowerpower levels. Initial Power, P_(i), refers to the amplitude ofradiofrequency power in Watts that is initially delivered to each of theablation electrodes (e.g., the proximal 133 and distal electrodes 132shown in FIGS. 8A, 8B, 8C, 8D, 8E, 9 and 10) at the beginning of theenergy delivery protocol. Initial Power may be selectable in a range of15 W to 50 W, preferably in a range of 20 W to 50 W, and may a havedefault setting of 35 W (e.g., when the flow rate is in a range of 10 to50 ml/min). First Electrode Pulse Width, PW1, is the duration of eachpulse of RF energy (i.e., ablative portion of waveform) delivered to thedistal electrode 132 and may be selectable in a range of 0.5-4 s (e.g.,1-3 s, preferably 2 s) and have a default setting of preferably 2 s.Second Electrode Pulse Width, PW2, is the duration of each pulse of RFenergy (i.e., ablative portion of waveform) delivered to the proximalelectrode 133 and may be selectable in a range of 0.5-4 s (e.g., 1-3 s)and have a default setting of preferably 2 s. Some embodiments may havemore than two electrodes and accordingly may have parameters of pulsewidth associated with each of them. The off period of an electrodeswaveform may equal the duration of the on period(s) of the remainingelectrode(s). In an embodiment having four electrodes, alternatingelectrodes (e.g., the first and third) may be synchronized together andasynchronous with the remaining electrodes (e.g., the second andfourth). The Total Therapy Time, t_(TOTAL), is the duration of time fromthe beginning of delivery of ablative energy to the end and may beselectable in a range of 60 s to 400 s (e.g. 120 to 200 s), preferably180 s. Minimum Therapy Time, is an optional portion of Total TherapyTime (e.g., less than or equal to) beginning at the start of delivery ofablative energy; if a temperature or impedance limit is reached beforeMinimum Therapy Time is complete then power may be decreased to theSecondary Power level or subsequent lower power level; if a temperatureor impedance limit is reached after Minimum Therapy Time is completethen power may be decreased to zero (e.g., ablative energy delivery maybe terminated). Lockout Period, t_(LO), is a period of time following anevent that triggers a reaction (e.g., a Temperature or Impedance Limitis passed, and the algorithm reacts by decreasing power) to allow tissuetemperature to respond to the reaction (e.g., decrease in temperature).During a Lockout Period the algorithm may ignore the temperature orimpedance measurements to either the electrode associated with thetrigger, or all electrodes unless they are indicative of a criticalerror such as a critical upper temperature limit, T_(CU), (e.g., 105° C.or higher), critical lower temperature limit, T C_(L), (e.g., 20° C. orlower), critical upper impedance limit, Z_(CU), (e.g., 800 or more Ohms,900 or more Ohms, 1000 or more Ohms, a user selectable value between 800and 2000 Ohms), or critical lower impedance limit (e.g., 50 Ohms orless) which may be indicative of damaged equipment. The Lockout Periodmay be selectable in a range of 2 s to 7 s, or alternatively the lengthof one pulse width up to the length of 4 pulse widths, and may have adefault setting of 5 s. Secondary Power, P2, refers to the amplitude ofradiofrequency power in Watts that is less than the Initial Power, forexample 5 to 10 W less than the Initial Power. The power level ischanged to Secondary Power if a Temperature, T_(L), or Impedance Limit,Z_(L) (e.g., in a range of 200 to 500 Ohms), is reached or passed, forthe electrode (e.g., distal 132 or proximal 133 electrode) associatedwith the temperature sensor (e.g., distal 140 or proximal 139temperature sensor) that sensed the Temperature Limit or with theelectrode through which the Impedance Limit was measured. Alternatively,if one of the temperature sensors measures temperature above theTemperature Limit, T_(L), power may be decreased to all of theelectrodes. Optionally, algorithm parameters may include further powerlevels that are less than the Secondary Power, such as a Tertiary PowerLevel, Quaternary Power Level, and so on. Alternatively, a user definedparameter may be a Power Decrement, P_(d), instead of Secondary Power.Power Decrement, P_(d), is an amount of decrease in power amplitudetriggered by an over temperature or over impedance limit and may beselectable in a range of 1 W to 30 W, with a default of 5 W. Optionally,the Power Decrement may be variable or be calculated as a percentage ofthe previous power level (e.g., a percentage in a range of 1% to 30%).In the event that Power is decreased, either to absolute levels such asSecondary Power or by Power Decrements, and a Minimum Power, P_(min),(e.g., in a range of 1 to 10 W, e.g., 5 W) is reached and temperature isstill above the Temperature Limit or impedance is still above theImpedance Limit, then the algorithm may react by a) terminating ablativepower to the electrode associated with the trigger and continue todeliver ablative power to the remaining electrode(s) either using thecurrent alternating waveform or in continuous RF, b) terminatingablative power to all electrodes, c) increase flow rate of theirrigation fluid, or d) adjust the Temperature Limit. If a treatment isterminated due to inability to maintain temperature below theTemperature Limit or impedance below the Impedance Limit or due to anyother error, the user may be instructed by the algorithm to repositionthe device, remove it for inspection, or inspect the equipment setup.

Saline may be pumped from an irrigation source through the catheter andout of irrigation ports 137 upon activation by a user. This may be donebefore the device is put in the patient to prime the irrigation lumen ortest functionality or while the device is being advanced into positionor during removal of the device and may facilitate delivery or removal,during which flow rate or pump speed may be selected by the user withina range of 0 to 50 mL/min. Optionally ablation will not start unlessflow is on within a range of 15 to 30 ml/min.

Saline tracking is a feature that has an algorithm that calculates avolume of saline that has been delivered to the patient, for example, bymultiplying flow rate and elapsed time or calculating the area under aplot of flowrate vs time, that saline has been delivered to thepatient's vasculature using said flow rate and displaying the volume ona user interface (e.g., on the computerized console). Furthermore, thealgorithm may determine if the portion of the catheter that deliversirrigation fluid is out of the body or in the body, either with a manualinput or with an automatic detection algorithm using one or more inputsignals such as temperature sensed by temperature sensors on thecatheter (e.g., sensor 139 or 140 in FIG. 8A), or monopolar impedance,or bipolar impedance. When the algorithm determines the catheter is inthe patient's body (or in a delivery sheath that is inserted into thepatient) any saline pumped by a pump connected to the computerizedconsole will be accounted for in the calculation of saline volumedelivered to the patient. When the algorithm determines the catheter isnot in the patient's body, any saline pumped by the pump connected tothe computerized console will not be accounted for in the calculation ofsaline volume delivered to the patient. This feature helps a userdetermine how much saline has been introduced to the patient's fluidsystem, which may be a concern for some patients. Optionally, a warningmay be triggered if a predetermined saline volume has been reached or isapproached. Saline irrigation flow rate may be turned on when the deviceis out of the body, for example to prime the irrigation lumen or to testthe catheter and irrigation system function. To determine how muchvolume is delivered to the body the saline tracking algorithm maydistinguish if the catheter is in or out of the body with manual input.This may be done by having the user press an actuator when the catheteris entered into the body that signals the algorithm to begin calculatingvolume when the pump is activated. If the catheter is removed from thebody the user may press an actuator to signal the algorithm that thecatheter is not in the body wherein calculation of accumulating salinevolume is paused. Any volume delivered outside of the body is notincluded in the calculation of saline volume delivered to this patient.If the catheter or other catheter is put back in the patient forsubsequent treatments any saline delivered to the patient is added tothe volume calculation by the user restarting tracking by pressing anactuator. Alternatively, the saline tracking algorithm may automaticallyidentify if the irrigated ablation catheter is in the body or not bymonitoring monopolar impedance measured between one or more ablationelectrodes and the grounding pad, or alternatively monitoring bipolarimpedance measured between two ablation electrodes. Monopolar impedancehas an advantage over bipolar impedance for detecting in vivo vs ex vivobecause monopolar impedance completes an electrical circuit from atleast one of the electrodes on the catheter through the body to adispersive grounding pad placed on the patient's skin, whereas bipolarimpedance completes a circuit from a first electrode on the catheterthrough a conductive medium to a second electrode on the catheter. Theconductive medium may be within the patient such as blood or tissue butit also could include saline or a conductive medium outside the body,for example if the electrodes are immersed in a saline bath or if salineis irrigated through the catheter and wets the electrodes closing thecircuit. However, bipolar impedance could still be used to detect achange in environment and be useful in a saline tracking algorithm. Avery low (non-ablative, e.g., 0.1 W) power may be delivered when anablation treatment is not running so impedance can be measured. Forexample in monopolar mode, if the catheter is in the body and connectedto the console and a grounding pad in electrical communication with theconsole is connected to the patient's skin, monopolar impedance may bewithin a certain range that is discernable from a catheter out of thebody. For example, as determined experientially, a monopolar impedancemeasurement within a range of 700-900 Ohms in monopolar mode mayindicate the distal region of the catheter having the electrodes andirrigation holes is in a sheath in the patient's vasculature; animpedance measurement that is a significant drop from the sheathedimpedance, for example in a range of 80 to 130 Ohms, may indicate thedistal region is in the vasculature and out of the sheath; above a highimpedance threshold (e.g., a high impedance threshold or 900 Ohms,higher than 2000 Ohms, higher than 3000 Ohms) in monopolar mode mayindicate the electrodes are out of the body, or that a grounding pad isincorrectly connected. Alternatively, bipolar impedance (e.g., measuredby passing current through conductive medium between two ablationelectrodes on the distal region of the catheter) measured in a range ofabout 300 to 600 Ohms (e.g., about 500 Ohms) may indicate the distalregion is in a sheath and in the body; or a bipolar impedance in a rangeof 60 to 80 Ohms may indicate the distal region is in the vasculatureout of the sheath; a high impedance threshold (e.g., higher than 600Ohms, higher than 900 Ohms, higher than 2000 Ohms, higher than 3000Ohms) may indicate the electrodes are out of the body, or that thecatheter's electrical circuit has been broken. The algorithm maydetermine that the distal region of the ablation catheter, where salineis released, is in the body if measured impedance is below the highimpedance threshold, wherein accumulating saline volume is accountedfor; and that the distal region is out of the body if measured impedanceis above the high impedance threshold, wherein saline pumped during thisscenario is not accounted for in the accumulated volume. Optionally,when a change of in vivo/ex vivo state has been detected the algorithmmay display a message asking the user to acknowledge the change.Optionally, a user may input a known volume of saline that has beeninjected by other means such as with a contrast solution injected from asyringe into the delivery sheath and the known volume may be added tothe accumulated volume calculation.

FIG. 20 shows a machine state diagram of an automatic saline trackingalgorithm. Beginning at a Main Therapy Screen 321 with the ablationcatheter connected to the console and out of the body and a groundingpad connected to the patient and console a user may press a button 325to enable saline tracking 326. This may begin automatic calculation ofsaline volume pumped wherein the calculation determines how much of thevolume of saline is deposited in the body and optionally how much ispumped while the catheter is out of the body. If the ablation catheteris inserted into the body the bioelectric impedance should drop 322 towithin the range indicating tissue contact and a message is displayedsuggesting that the user start saline tracking 323. The user may press abutton to acknowledge 324 the message which tells the algorithm toinclude the accumulating pumped saline to the total accumulated volumeof saline deposited in the body. If the catheter is removed from thebody an impedance rise to a level out of the range associated with bodycontact is measured 327 and a message is automatically displayed tosuggest the user Pause saline tracking 328. The user may press a buttonto acknowledge 329 the message which tells the algorithm to exclude theaccumulating pumped saline to the total accumulated volume of salinedeposited in the body. Furthermore, a user may press a button 330 at anytime to pause saline tracking, or to pause including the pumped salinevolume in the calculation of saline deposited into the body 331.Alternatively, instead of automatically defining that the catheter is inthe body based on impedance, an algorithm may alert the user that itthinks the catheter is out of the body and the user may manually selectthat flow shall be excluded from the saline tracking total. A resetactuator may be pressed by a user to reset the total volume to zero.

An alternative saline tracking algorithm may ignore a quick increase inimpedance within a predetermined amount that may be caused by theinjection of contrast solution or saline in the vicinity of the ablationelectrode(s) while the catheter is in the body to avoid a falsedetermination of removal. To distinguish the difference betweeninjecting contrast solution or saline and removing or inserting thedistal region of the catheter from the patient, when a large change inimpedance is detected, the algorithm may have two impedance thresholdsthat are used depending on whether the system is in in vivo or ex vivomode. A first impedance threshold (e.g., in a range of 400 Ohms to 600Ohms, about 500 Ohms) may be used if the catheter is not in thepatient's body (i.e., ex vivo) to automatically indicate that thecatheter has been inserted into the body when impedance drops below thisfirst threshold. A second impedance threshold (e.g., in a range of 800Ohms to 3000 Ohms, about 900 Ohms) may be used if the catheter is in thepatient's body (i.e., in vivo) to automatically indicate that thecatheter has been removed from the body when impedance rises above thissecond impedance threshold. For example, the ablation catheter may beout of the patient and impedance may be above the second threshold, say900 Ohms; if the saline pump is running the algorithm determines thatthe catheter is not in the body and no saline volume is included in anaccumulation calculation; the catheter may be inserted into the patientand impedance may drop below the first threshold, say 500 Ohms, whereinthe algorithm determines the catheter is in the body and any pumpmovement is accounted for in the accumulation calculation; injection ofsaline or contrast may raise impedance above the first threshold butsince the catheter is in the body the algorithm determines the rise doesnot indicate removal so any pump movement continues to be accounted forin the accumulation calculation; if the catheter is removed from thebody impedance will rise above the second threshold, say 900 Ohms, andthe tracking algorithm will determine the catheter has been removed andany pump movement will not be accounted for in the accumulationcalculation. Optionally, the first and second thresholds may be adjustedor selected in user settings. The catheter may be indicated for use witha consistent concentration of saline, for example 0.90 Normal Saline,for the algorithm to function properly.

In addition to calculating accumulated saline injected, the algorithmmay optionally change other feature behaviors depending on whether thesystem is in the in vivo or ex vivo mode, for example as described inTable 1.

TABLE 1 Ex vivo Feature In vivo behavior behavior Saline volume trackingactive paused Require confirmation to stop enabled disabled pump Reminduser to turn on pump Triggered upon entry to in n/a if not running vivomode Remind user Pump Prime not Triggered upon entry to in n/a completedsince last power vivo mode cycle Require confirmation to run In vivoWarning Message Prime Notify user that pump is still n/a Triggered uponrunning entry to ex vivo mode RF energy delivery Allowed RestrictedPrime Mode (bypass pump Restricted Allowed bubble detector)

Another use of bipolar impedance monitoring by an algorithm may be usedto display a message to the user to check if the dispersive groundingpad is not correctly connected if bipolar impedance is low (e.g., lessthan 500 Ohms) and monopolar impedance is high (e.g., above 900 Ohms).

Another use of bipolar impedance monitoring by an algorithm may be usedto display a message to the user to check if there is an open circuit onone or both electrodes, if bipolar impedance is high (e.g., above 900Ohms), and the irrigation pump is running, and the system is in in vivomode.

During the Ablation Mode Algorithm, the pump may be activated so salineis irrigated from irrigation ports 137 with a flowrate in a range of 15to 30 ml/min before ablation energy begins to be delivered, for examplefor a time of 5 s. Then radiofrequency electrical energy (RF), forexample having a frequency in a range of 350 to 500 kHz, is deliveredfrom the computerized energy console to a first of the plurality ofelectrodes (e.g., the distal electrode 132) in monopolar mode (i.e.,returned through a grounding pad) with the Initial Power for a durationof a pulse width (e.g., the First Electrode Pulse Width). Then the firstelectrode (e.g., distal electrode) enters its off period of the waveform(e.g., having a power of 0 W or a low power less than 1 W) while RF isdelivered to a second electrode (e.g., the proximal electrode) startingat the Initial Power for a duration of the Second Electrode Pulse Width.Optionally, if the ablation device has more than two electrodes powermay be then delivered to the subsequent electrode(s) for an accordingpulse width before repeating power delivery to the first electrode.Alternatively, power may be delivered to the electrodes in other ordersor combinations without deviating from the spirit of the disclosureherein. RF power continues to be multiplexed through each electrode forthe Total Therapy Time unless an event is triggered that titrates orstops delivery of ablative RF.

Throughout the Ablation Mode Algorithm and optionally before or after,temperature may be measured by the temperature sensors (140 and 139 inFIGS. 8A, 8B, 9, and 10) and displayed on the console. During theAblation Mode Algorithm these temperatures may be compared to apredefined Temperature Limit, T_(L), which may be in a range of 40° C.to 95° C., preferably 90° C. Since the space in the vessel around theelectrodes and temperature sensors is irrigated the measuredtemperatures can be expected to be less than the hottest tissuetemperature. Due to the variability of vessel size and shape therelationship between measured temperature and the hottest tissuetemperature or ablation volume may vary. However, a measured temperaturethat is higher than the Temperature Limit may be an indication of toomuch power. The Temperature Limit may be considered as a safety controlwhere measured temperature above the limit needs to be reduced. However,if measured temperature is below the limit it is not necessarily anindication of low tissue temperature. If the measured temperatures arebelow the Temperature Limit throughout the Total Therapy Time then RFPower remains at the Initial Power. If one of the measured temperaturesis above or optionally equal to the Temperature Limit, T_(L), duringtreatment (total therapy time) t_(TOTAL), or optionally before MinimumTherapy Time is complete, then power may be decreased to the SecondaryPower, P2, preferably for the active electrode as shown in FIG. 19, oralternatively for the electrode associated with said measuredtemperature or all electrodes. The measured temperature is expected todrop below the Temperature Limit within about 5 seconds (or about 2 to 3pulse widths) of the power decrease, however if it does not or if itdoes but then raises to or above the Temperature Limit again prior tocompletion of the Total Therapy Time (or optionally the minimum therapytime) then power may be decreased to 0 W or a low level less than 1 Wpreferably to all electrodes, or alternatively to the active electrodeor the electrode associated with the measured temperature.Alternatively, power may be decreased to the Tertiary Power and so on.Following completion of the Minimum Therapy Time if any of the measuredtemperatures reaches or exceeds the Temperature Limit then power may bedecreased to 0 W or a low level less than 1 W instead of titrating powerto a lower ablative level.

Optionally, the Ablation Mode Algorithm may further have an ImpedanceLimit, Z_(L), which may be in a range of 200 to 500 ohms, preferably500, which may be an indication of tissue desiccation. If monopolarimpedance measured from one of the plurality of electrodes in electricalcommunication with the grounding pad, rises above the Impedance Limitdelivery of ablative energy to the associated electrode may terminatedto avoid steam formation or injury. Optionally or additionally, if anImpedance Limit is passed before minimal therapy time is complete thenpower of the ablative RF energy may be reduced to the Secondary Power oroptionally other lower power levels if there are subsequent occurrences.As shown in FIG. 19, if impedance for all electrodes remains below theImpedance Limit, Z_(L), and above a Critical Low Impedance Limit,Z_(CL), then there are no resulting changes to power for each electrode.

Optionally, if temperature or impedance for a particular electrode goesabove the Temperature Limit or Impedance Limit when the secondary poweris being delivered then ablative RF power may drop to 0 W preferably forthe active electrode, or alternatively for the electrode associated withthe sensor or for all electrodes.

Optionally, the Total Therapy Time or Minimum Therapy Time (if included)may be extended if power has been decreased to the Secondary Power, oroptional subsequent lower power levels, for example match the amount ofenergy being delivered if power were not decreased.

In addition to the Temperature and Impedance Limits the algorithm mayhave an Upper Critical Temperature Limit, T_(CU), Lower CriticalTemperature Limit, T_(CL), Upper Critical Impedance Limit, Z_(CU) andLower Critical Impedance Limit, Z_(CL). An Upper Critical TemperatureLimit, T_(CU), may be used to identify a damaged temperature sensor oran ultimately high tissue temperature above which is not desirable, andmay be equal to or above 105° C. A Lower Critical Temperature Limit,T_(CL), may indicate something is incorrect about placement or devicedamage and may be equal to or below body temperature (e.g., 35° C.). AnUpper Critical Impedance Limit, Z_(CU), may be used to identify damageto the catheter such as broken wires or improperly applied ground padand may be in a range of 800 to 2000 Ohms. A Lower Critical ImpedanceLimit, Z_(CL), may be used to identify damage to the catheter such asshort circuit or a damaged electrode and may be equal to or below 20Ohms.

Optionally, an energy delivery algorithm may have a bipolar RF componentwhere RF electrical current passes from the first electrode to thesecond electrode (bipolar mode). Bipolar RF concentrates current densitybetween the two electrodes which may result in an ablation pattern thatheats tissue between the electrodes greater than the two electrodesdelivering monopolar RF independently from one another. A bipolar RFcomponent may be added to the beginning or end of a MultiplexedMonopolar RF period. For example, a bipolar RF component may have aduration in a range of 30 s to 120 s, preferably about 60 s, and deliverpower at an initial level in a range of 10 to 50 W (e.g., 20 to 35 W,preferably about 30 W) and be delivered either before or after amultiplexed monopolar RF treatment.

Alternatively and optionally, an ablation waveform may be similar to theMultiplexed Monopolar RF algorithm but have an additional pulse widthwherein the electrodes deliver Bipolar RF. For example, a bipolar pulsewidth may be in a range of 0.5 to 5 s (e.g., 2 s). The waveform may havean alternating cycle of monopolar RF from a first electrode for a firstpulse width, monopolar RF from a second electrode for a second pulsewidth, and bipolar RF between the first and second electrodes for abipolar pulse width that repeats. If the ablation catheter has more thantwo electrodes the waveform may include a repeating cycle of monopolarRF to each electrode for respective pulse widths and bipolar RF betweeneach adjacent pair of electrodes for bipolar pulse widths.

An alternative embodiment of an Ablation Energy Delivery Algorithm usedto create a desired lesion for GSN ablation, is referred to as“Sequential Monopolar with Bipolar Fill”, wherein ablative RF energy isdelivered in monopolar mode to a first ablation electrode (e.g., thedistal electrode 132 shown in FIGS. 1, 2, 8A, 8B, 9, and 10) for a FirstElectrode Monopolor Duration, then to a second ablation electrode (e.g.,the proximal electrode 133) for a Second Electrode Monopolar Duration,then ablative RF energy is delivered in bipolar mode between the firstand second electrodes for a Bipolar Duration and with an Initial BipolarPower. If temperature measured by a temperature sensor associated withthe electrode receiving ablation energy raises above an Upper MonopolarTemperature Limit the Initial Monopolar Power of RF energy may bedecreased to a Secondary Monopolar Power or alternatively be decreasedby a Power Decrement. If the temperature rises above the upperTemperature Limit again while the lower power is being delivered thenthe power may be decreased again, either to a Tertiary Power or by thePower Decrement. Optionally, a user may define parameters such asInitial Power to each ablation electrode, First and Second ElectrodeMonopolor Durations, Power Decrement or Secondary, Tertiary etcMonopolar Power. Likewise, during the Bipolar phase the Initial BipolarPower may be decreased to a Secondary Bipolar Power or by a PowerDecrement if measured temperature from either of the temperature sensorsassociated with the activated electrodes rises above an Upper BipolarTemperature Limit.

Initial Monopolar Power is the amplitude of RF power that is initiallydelivered to either ablation electrode during the monopolar phases andmay be selectable in a range of 20 W to 50 W, with a default setting of25 W.

First Electrode Monopolor Duration is the amount of time that ablativeRF energy is delivered to the first electrode in Monopolar mode and maybe selectable in a range of 30 s to 180 s, with a default setting of 60s.

Second Electrode Monopolor Duration is the amount of time that ablativeRF energy is delivered to the second electrode in Monopolar mode and maybe selectable in a range of 30 s to 180 s, with a default setting of 60s.

Secondary Monopolar Power is the amplitude of RF power that is lowerthan the Initial Monopolar Power, triggered by measured temperaturerising above the Upper Temperature Limit. It may be selectable in arange of 10 W to 50 W, as long as it is below the Initial MonopolarPower, with a default setting of 20 W.

Monopolar Power Decrement, an alternative to Secondary Monopolar Power(and optionally Tertiary etc.), is the amount of decrease in Powertriggered by measured temperature rising above the Upper MonopolarTemperature Limit and may be selectable in a range of 1 to 20 W, with adefault setting of 5 W.

Initial Bipolar Power is the amplitude of RF power that is initiallydelivered to two ablation electrodes (e.g., the two electrodes that werepreviously activated with monopolar RF) during the bipolar phase and maybe selectable in a range of 10 W to 50 W, with a default setting of 20W.

Bipolar Duration is the amount of time that ablative RF energy isdelivered to the two electrodes in Bipolar mode and may be selectable ina range of 10 s to 180 s, with a default setting of 20 s.

Secondary Bipolar Power is the amplitude of RF power that is lower thanthe Initial Bipolar Power, triggered by measured temperature risingabove the Upper Bipolar Temperature Limit. It may be selectable in arange of 5 W to 50 W, as long as it is below the Initial Bipolar Power,with a default setting of 15 W.

Bipolar Power Decrement, an alternative to Secondary Bipolar Power (andoptionally Tertiary etc.), is the amount of decrease in Power triggeredby measured temperature rising above the Upper Bipolar Temperature Limitand may be selectable in a range of 1 to 20 W, with a default setting of5 W.

Upper Monopolar Temperature Limit is a threshold temperature thatmeasured monopolar temperature is compared to during a monopolar phase.It may be selectable within a range of 60 to 90° C., with a defaultsetting of 90° C.

Upper Bipolar Temperature Limit is a threshold temperature that measuredbipolar temperature is compared to. It may be selectable within a rangeof 60 to 90° C., with a default setting of 90° C.

Optionally, if an Upper Temperature Limit is passed during either amonopolar or bipolar phase Initial Power may be decreased to theSecondary Power or by the Power Decrement and the Duration may berepeated, optionally with the electrodes in the same position. If theUpper Temperature Limit is passed a subsequent time the therapy may beterminated with an error message. The user may attempt an ablationprocedure with the electrodes repositioned or with a new catheter.

Optionally, the algorithm may have an Upper Monopolar Impedance Limit,which is a threshold impedance that measured monopolar impedance iscompared to during a monopolar phase. It may be selectable within arange of 150 to 300 Ohms, with a default setting of 200 Ohms.

Optionally, the algorithm may have an Upper Bipolar Impedance Limit,which is a threshold impedance that measured bipolar impedance iscompared to during the bipolar phase. It may be selectable within arange of 100 to 300 Ohms, with a default setting of 150 Ohms.

The disclosure that follows provides some exemplary methods of use andsteps thereof. Some embodiments of a method of use may include one ormore of the following steps, the order of which may in some instances bevaried, and not all steps of which need necessarily be performed.Methods herein may include interventional access, which may include oneor more of the following treat the patient with an anti-coagulationregimen that is appropriate for venous interventional procedures; placea return electrode on the patient's right chest; follow standardtechniques for femoral, subclavian, or jugular vein puncture, guide wireinsertion, and sheath placement using heparinized saline whereappropriate; place 0.035 exchange length guide wire (e.g., Cordis AmpathSuper Stiff 260 cm or equivalent); advance a 6 F general purposecatheter (e.g. JR4 or equivalent) over the guide wire to the azygousvein ostium; using the 6 F general purpose catheter, inject a bolus ofradiopaque contrast to identify the azygos vein ostium usingfluoroscopy; engage the azygos vein ostium with the guide wire and 6 Fgeneral purpose catheter and advance the guide wire through the valve(if applicable) into the azygos vein; exchange the 6 F general purposecatheter for an azygos access sheath, wherein the azygos access sheathmay be 9 F and at least 100 cm long (e.g., Arrow 9 F Super Arrow FlexIntroducer Sheath or equivalent); position the azygos access sheathapproximately to the T9 level; adjust the C-arm off the vertical axis toobtain the optimal view of the azygos vein tree via shooting contrastprior to introduction of the Ablation Catheter; load a 0.014 exchangelength guide wire (e.g. ChoICE Pt LS Floppy or equivalent) into theazygos access sheath; and advance the 0.014 guide wire and deep seatinto first target intercostal vein (e.g., T11 intercostal vein).

Methods herein may include device, generator, and accessory preparation,which may include one or more of the following steps: inspect thecatheter package prior to use; open the Ablation Catheter package usingsterile technique; while maintaining sterility, remove the Catheter fromits package and place in a sterile field; visually inspect theelectrodes and ablation catheter carefully for integrity and overallcondition; fill a 10 cc or larger syringe with saline and connect thesyringe to the guidewire lumen hub on the handle of the ablationcatheter. Flush the guidewire lumen with the saline to remove all air;prepare the ablation catheter by connecting the ablation catheterirrigation line to a 3-way stopcock, connecting the tube set to the3-way stopcock and connecting the saline spike on a hanging sterilesaline bag, and ensuring the stopcocks on the saline inlet and salineoutlet lines are in the open position; place the irrigation pump tubinginto the pump, through the bubble detectors and close the pump door;power ON the Generator (also referred to as a computerize console) andinitialize the pump; flush the irrigation lumen of the ablation catheterusing the pump to pump the saline through the irrigation lumen; confirmthat the irrigation ports are patent; purge the tubing and ablationcatheter of air bubbles; watch the saline tubing and Catheter tip forbubbles and continue to de-bubble until there is no air in the ablationcatheter irrigation lumen and tube set; to avoid occlusion of theirrigation conduits and prevent ingress of air into the ablationcatheter, the ablation catheter may be continuously irrigated whenwithin the vasculature, for example at a rate 2 mL/min; irrigation mayonly be stopped after removal of the ablation catheter from the body;confirm user selectable ablation parameters on the Generator; plug theablation catheter with a cable into the RF Generator; observe connectorpolarity;

Methods herein may include Ablation Catheter Insertion and AblationEnergy Delivery, which may include one or more of the following steps:with the 0.014 guide wire deep seated in the first target intercostalvein, advance the ablation catheter over the guide wire into theintercostal vein; initiate saline tracking (examples of which are setforth herein) from the Generator once the ablation catheter is insertedinto the patient; the ablation catheter may be passed from a peripheralvessel to the desired position with the aid of fluoroscopy; the ablationcatheter saline infusion rate may be increased to a maximum of 50 mL/minto assist with device entry to the target intercostal vein; place theproximal marker at the anterior midline of the vertebrae in the AP view(if possible); if the azygos to intercostal vein ostium is to thepatient's right of midline, advance the device so the proximalradiopaque marker is in the azygos vein proximal to the ostium to theintercostal vein and approximately at the patient's midline; rotate theC-arm to RAO30 (or an appropriate angle that maximizes the projectedlength between the proximal and distal radiopaque markers) and confirmthat the distal marker is not past the costovertebral joint, and adjustas appropriate; confirm that a valid impedance reading (e.g., within 80to 150 Ohms in monopolar mode, or within 60 to 80 Ohms in bipolar mode)is displayed for both electrodes on the Generator; activate a salineinfusion rate of 15 ml/min to 30 ml/min before initiating ablativeenergy delivery; a recommended saline infusion rate during ablation maybe 15 ml/min; The saline infusion rate can be adjusted after initiationof RF delivery to within 15 ml/min to 30 ml/min; initiate the RFablation mode algorithm from the Generator; monitor the impedancedisplay on the RF Generator, before, during, and after RF powerdelivery; if a sudden rise in impedance is noted during RF delivery thatdoes not exceed the preset limit, manually discontinue the powerdelivery; clinically assess the situation; if necessary, remove theablation catheter and inspect it for damage; in case of a steam pop orautomatic shut off, discontinue RF and remove the ablation catheter,terminate saline tracking from the RF Generator and perform a visualinspection, checking for coagulum, charring, or other catheter defects;confirm saline infusion rate and flush the ports prior to reinsertion inthe patient, resuming saline tracking once inserted; if the ablationcatheter has defects, exchange it for a new one; re-position theablation catheter and attempt another RF application; optionally, nomore than two 180 s RF applications should be completed at a singletarget site; if the pump alarms and stops the irrigation, immediatelyremove the Catheter from the patient and inspect and re-flush theablation catheter; when the ablation in the first target intercostalvein (e.g., T11) is finished, remove the guide wire and ablationcatheter from the first target intercostal vein and keep in the azygosaccess sheath in place; the ablation catheter saline infusion rate maybe increased to a maximum of 50 cc/min to assist with device removalfrom the target intercostal vein; the ablation catheter may be removedfor inspection; deliver contrast agent to visualize a second targetintercostal vein (e.g., T10) from the azygos access sheath; repeatAblation Catheter Insertion and Ablation Energy Delivery steps toadvance the ablation catheter over the guide wire into the second targetintercostal vein and ablate; when the ablation in the second targetintercostal vein is finished, withdraw the ablation catheter into the 9F azygos access sheath and deliver contrast from the azygos accesssheath to obtain a fluoroscopic image of the azygos tree.

Methods herein include device withdrawal, which may include one or moreof the following steps: withdraw the ablation catheter into the 9 Fazygos access sheath and out of the patient; terminate saline tracking;it may be helpful to disconnect the connector cable; inspect theablation catheter; withdraw the azygos sheath from the patient and closethe venous puncture; after use, dispose of the devices in accordancewith hospital, administrative, and/or local governmental policy.

In any of the methods herein, including ablation confirmation testsherein, not all of the steps need necessarily to be performed. And someof the steps may occur in different orders. It is of note that theprocedures herein are intending to target particular nerves or nerveroots, and are doing so from particular target veins, and even withinthose veins are placing ablation elements or members within certainregions. The anatomical regions that are being accessed and targetednecessitate certain design requirements. In other treatments that aretargeting different anatomical locations for placement, and targetingdifferent target nerves, the device design constraints for thoseapproaches are very different, and thus the devices that can be used inthose treatments may be very different. The disclosure herein thusprovides specific reasons for designing particular devices, and thosereasons include being able to effectively carry out the treatmentsspecifically set forth herein.

While the above description provides examples of one or more processesor apparatuses, it will be appreciated that other processes orapparatuses may be within the scope of the accompanying claims.

To the extent any amendments, characterizations, or other assertionspreviously made (in this or in any related patent applications orpatents, including any parent, sibling, or child) with respect to anyart, prior or otherwise, could be construed as a disclaimer of anysubject matter supported by the present disclosure of this application,Applicant hereby rescinds and retracts such disclaimer. Applicant alsorespectfully submits that any prior art previously considered in anyrelated patent applications or patents, including any parent, sibling,or child, may need to be re-visited.

Specific embodiments described herein are not intended to limit anyclaim and any claim may cover processes or apparatuses that differ fromthose described below, unless specifically indicated otherwise. Theclaims are not limited to apparatuses or processes having all of thefeatures of any one apparatus or process described below or to featurescommon to multiple or all of the apparatuses described below, unlessspecifically indicated otherwise. It is possible that an apparatus orprocess described below is not an embodiment of any exclusive rightgranted by issuance of this patent application. Any subject matterdescribed below and for which an exclusive right is not granted byissuance of this patent application may be the subject matter of anotherprotective instrument, for example, a continuing patent application, andthe applicants, inventors or owners do not intend to abandon, disclaimor dedicate to the public any such subject matter by its disclosure inthis document.

Additional Examples

A first additional example is a method of characterizing the position ofa patient's azygos vein relative to a portion of the patient's spine,comprising: while imaging at least a portion of the patient's spine;intravascularly delivering a device into a patient's azygos vein;performing at least one of: injecting a radiopaque contrast agent (e.g.,dye) from the device into the patient's vasculature (e.g., into theazygos vein and/or one or more intercostal veins) to visualize thevasculature relative to a position of the spine, or identifying theposition of at least a portion of the device relative to a portion ofthe spine, to thereby characterize (e.g., qualify and/or quantify) theposition of the patient's azygos vein relative to a portion of the spine(e.g. relative to a midline of the spine).

In this first additional example, imaging may comprise imaging in ananterior-to-posterior view.

This first additional example may further comprise determining a lateralposition of a patient's azygos vein, where it meets an intercostal vein,relative to the patient's spine. Determining a lateral position of thepatient's azygos vein may be performed while imaging the patient'sazygos vein. Imaging may comprise radiographic imaging (e.g.fluoroscopy) after injecting a radiopaque contrast agent (e.g., dye)from the device into the patient's vasculature. Determining a lateralposition may be used to determine where to place an ablation catheterrelative to the intercostal vein, as part of an ablation procedure(optionally to ablate a GSN).

A second additional example is a method that includes assessing aposition of a patient's azygos vein to determine if it is centered,right-biased (to the patient's right of center), or left-biased (to thepatient's left of center). Assessing a position of the patient's azygosvein may be performed while imaging the patient's azygos vein. Imagingmay comprise radiographic imaging (e.g., fluoroscopy). Imaging maycomprise imaging in an anterior-to-posterior view. Assessing theposition may be used to determine where to place an ablation catheter aspart of an ablation procedure (optionally intended to ablate a GSN).

In this second additional example, an assessing step can be used todetermine where to place a radiopaque marker of an ablation catheter(optionally a proximal radiopaque marker), wherein the ablation catheterincludes an ablation element distal to the radiopaque marker.

In this second additional example, the assessing step is used todetermine whether to place the radiopaque marker at an ostium where theazygos vein meets an intercostal vein, or at (including substantiallyat) a midline of the spine.

In this second additional example, if an assessing step indicates thatthe azygos vein is right-biased or centered (including substantiallycentered), the method may include positioning the radiopaque marker atan ostium where the azygos vein meets the intercostal vein.

In this second additional example, if the assessing step indicates thatthe azygos vein is left-biased, the method may include positioning theradiopaque marker at or substantially at a midline of the spine (forexample, as determined in an anterior-to-posterior imaging view).

In this second additional example, the assessing step may be used todetermine where to place an ablation element (e.g., one or moreelectrodes) that is part of the ablation catheter.

In this second additional example, the method may further compriseassessing a position of a distal radiopaque marker relative to at leastone or more of a portion of the spine, a rib, or a costovertebral joint.The method may further comprise retracting the ablation catheterproximally if the assessment indicates that the distal radiopaque markeris positioned too far distally, which thereby indicates the ablationelement is positioned too far distally. The method may further ensurethat the distal radiopaque marker is not further distally than thecostovertebral joint.

A third additional example is a method of intravascularly positioning anablation catheter for GSN ablation, comprising: positioning an ablationcatheter in one or more of an intercostal vein (e.g. T9, T10, or T11)and an azygos vein, wherein the position of the ablation catheter isselected based on a characterized relative position of a portion of thespine and a location of the azygos vein where it meets the intercostalvein.

A fourth additional example is a method of characterizing a position ofa distal section of an ablation catheter to facilitate placement of atleast a portion of the ablation catheter in an intercostal vein,comprising: positioning an ablation catheter in a patient's intercostalvein (e.g. a T9, T10, or T11 intercostal vein); while imaging a portionof the patient that includes the intercostal vein and a portion of thespine, determining a location of one or more components of the ablationcatheter relative to one or more of a portion of the spine, a rib, or acostovertebral joint.

A fifth additional example is a method of any claim herein, comprisingaccessing venous vasculature at the patient's jugular vein or femoralvein with an access introducer sheath (e.g. 12 F).

A sixth additional example is a method of any claim herein, comprisingdelivering a delivery sheath (e.g., 9 F sheath) to an azygos vein (e.g.,to one or two thoracic levels above the target intercostal).

A seventh additional example is a method of any claim herein, comprisingdelivering contrast agent to show a location of an azygos vein and oneor more intercostal veins while imaging the azygos vein and one or moreintercostal vein.

Any of additional examples may include an imaging step that comprisesimaging in an anterior-to-posterior direction (e.g., with a C-arm in anAP position).

Any of additional examples may include positioning a C-arm in a RightAnterior Oblique angle.

Any of additional examples may include positioning a C-arm in a range of20 degrees to 70 degrees, such as 30 to 60 degrees.

Any of additional examples may include positioning a C-arm at an anglethat maximizes a projected distance between first and second axiallyspaced locations on the ablation catheter (e.g., locations of proximaland distal radiopaque markers).

Any of additional examples may include assessing if a RO marker (e.g., adistal RO marker) is at or proximal to a particular anatomical location(e.g. a costovertebral joint).

Any of additional examples may include, if the marker is at or proximalto the particular anatomical location, continuing with an ablationprocedure (e.g. ablating tissue). If the marker is not at or proximal tothe particular anatomical location, the method may include moving theablation catheter within the intercostal vein. If the marker is not ator proximal to the particular anatomical location, the method mayinclude generating ablative energy within a proximal ablation element(e.g. coiled electrode) but not with a distal ablation element (e.g.coiled electrode).

An eighth additional example is an ablation catheter sized andconfigured such that a distal section of the ablation catheter can beadvanced into a T9, T10, or T11 intercostal vein from an azygos vein,and adapted to deliver ablative energy, comprising: an elongate shaftwith a length such that a distal section of the catheter can bepositioned in a T9, T10, or T11 intercostal vein; and the distal sectioncomprising an electrically conductive flexible ablation element carriedby the elongate shaft, the electrically conductive flexible ablationelement (which may comprise more than one ablation element) having alength from 5 mm-20 mm, and the distal section having an OD (at least ina delivery configuration) from 1.5 mm-3 mm.

A ninth additional example is an ablation catheter sized and configuredsuch that a distal section of the ablation catheter can be advanced intoa T9, T10, or T11 intercostal vein from an azygos vein, and adapted todeliver ablative energy, comprising: an elongate shaft with a lengthsuch that a distal section of the catheter can be positioned in a T9,T10, or T11 intercostal vein; and the distal section comprising anelectrically conductive flexible ablation element carried by theelongate shaft.

In this ninth additional example, the ablation element may comprise afirst ablation element axially spaced from a second ablation element,the first and second ablation elements carried by the shaft. The firstablation element may have a coiled configuration, and wherein the secondablation element may have a coiled configuration. A coiled configurationof the first ablation element may be the same in all regards as a coiledconfiguration of the second ablation element. A coiled configuration ofthe first ablation element may be different than a coiled configurationof the second ablation element in at least one way.

In this ninth additional example, the first ablation element may have adifferent length than the second ablation element.

In this ninth additional example, the first ablation element may have adifferent coil direction (e.g. left handed vs right handed) than thesecond ablation element.

In this ninth additional example, the first ablation element may have adifferent pitch than the second ablation element.

In this ninth additional example, the first ablation element may have adifferent wire thickness than the second ablation element.

In this ninth additional example, an OD of the distal section at thelocation of the first ablation element may be different than an OD ofthe distal section at the location of the second ablation element.

In this ninth additional example, a first ablation element and a secondablation element may each have either a curvilinear (e.g. circular) orrectilinear (e.g., rectangular) cross sectional outer profile.

In this ninth additional example, a first ablation element and a secondablation element may be a superelastic material such as nitinol.

In this ninth additional example, a first ablation element and a secondablation element may be sufficiently flexible to allow the distalsection to be advanced from an azygos vein into one of a T9, T10, or T11intercostal vein.

In this ninth additional example, at least one of a first and secondablation elements may be made from a laser cut tubular element (e.g., anitinol tube).

In this ninth additional example, at least one of a first and secondablation elements may comprise a wire mesh or braid.

In this ninth additional example, at least one of a first and secondablation elements may be a ring electrode having a length not more than5 mm, optionally around 3 mm.

In this ninth additional example, each of a first and second ablationelements may have a length from 1 mm-12 mm, optionally from 2 mm-12 m,optionally from 5 mm-12 mm, optionally from 6 mm-11 mm, optionally from7 mm-10 mm, such as around 8 mm.

In this ninth additional example, an axial spacing between a first andsecond ablation elements may be from 0 mm-8 mm, such as from 0 mm-5 mm,such as from 0.5 mm-5 mm, such as from 1 mm-4 mm.

In this ninth additional example, an ablation element total axial lengthmay be from 1 mm-25 mm, optionally from 2 mm-22 mm, optionally from 5mm-20 mm, optionally 8 mm-20 mm, optionally 10 mm-20 mm, optionally 10mm-18 mm, optionally, preferably 10 mm-15 mm.

In this ninth additional example, the ablation element, and optionallyboth of a first and second ablation elements, may have an expandablediameter.

In this ninth additional example, the ablation element may comprise aplurality of ablation elements, of which first and second ablationelements may be part of and may define the entirety of the plurality ofablation elements.

In this ninth additional example a plurality of ablation elements may beconfigured to be independently energized in monopolar mode (with aground pad).

In this ninth additional example, any two of a plurality of ablationelements may be configured to be energized in bipolar mode.

In this ninth additional example, the catheter may include a temperaturesensor disposed between the first and second ablation elements andcarried by the shaft.

In this ninth additional example, the catheter may further comprise oneor more of a temperature sensor distal to a distal ablation element, ora temperature sensor proximal to a proximal ablation element.

In this ninth additional example, the catheter may include at least oneirrigation port in fluid communication with an irrigation lumen that isconnectable to a fluid source at a proximal region of the ablationcatheter. The ablation catheter may further comprise a second irrigationport distal to the proximal ablation element.

In this ninth additional example, the catheter may include one or moreirrigation ports between a distal end and a proximal end of a distalablation member, optionally between the windings of a coiled distalablation member.

In this ninth additional example, the catheter may comprise one or moreirrigation ports between a distal end and a proximal end of a proximalablation member, optionally between the windings of a coiled proximalablation member.

In this ninth additional example, the catheter may include one or moreirrigation ports under any of the flexible ablation elements, such as adistal ablation element and/or a proximal ablation member.

In this ninth additional example, the catheter may further comprise adeployable element carried by the shaft (optionally expandable). Adeployable element may be distal to the ablation element, optionallydistal to a distal ablation element. A deployable element may beinflatable, and wherein the shaft may include an inflation port withinthe inflatable deployable element. A deployable element may have adelivery configuration and a deployed configuration with an OD greaterthan the delivery configuration. A deployable element may have an ODfrom 3-6 mm in the deployed configuration, such as 4 mm-6 mm. Adeployable element may have an OD that is equal to or greater than theOD of the shaft in the distal section by no more than 0.2 mm. Adeployable element may comprise at least one of the following: aballoon, a bellowed member, or a coated stent or coated stent-likedevice (e.g., a reinforcing member coated with a one or more layers ofmaterial).

In this ninth example, the ablation catheter may further comprise aproximal deployable element carried by the shaft proximal to theablation element, which may be proximal to a proximal ablation element.A proximal deployable element may be inflatable, and wherein the shaftmay include an inflation port within the proximal deployable element. Aproximal deployable element may have a delivery configuration and adeployed configuration with an OD greater than the deliveryconfiguration. A deployable element may have an OD from 4-10 mm in thedeployed configuration, and optionally larger than an OD of a distaldeployable member. A proximal deployable element may have an OD that isequal to or greater than the OD of the shaft in the distal section by nomore than 0.2 mm. A proximal deployable element may comprise at leastone of the following: a balloon, a bellowed member, or a coated stent orcoated stent-like device (e.g., a reinforcing member coated with a oneor more layers of material).

In this ninth additional example, the catheter may include a centraldeployable element. A central deployable element may include any of thefeatures, including any combination thereof, of a distal or proximaldeployable member herein.

In this ninth additional example, the catheter is configured fortransvascular ablation of a GSN. The ablation catheter may include adistal section that includes the distal-most 7 cm of the ablationcatheter. The ablation element may be adapted to create an ablationhaving a length in a range of 5 mm to 25 mm.

In this ninth additional example, a distal section may be adapted forflexibly traversing a bend from an azygos vein to a T9-T11 intercostalvein (e.g., having a radius of curvature >=5 mm, angle as much as 120degrees.

In this ninth additional example, an outer diameter of the distalsection (at least in a delivery state) is in a range of 1.5 to 3 mm.

In this ninth additional example, the ablation catheter may furthercomprise a guidewire lumen within the elongate shaft.

In this ninth additional example, a total length of the ablation element(which may comprise a plurality of individual ablation elements) may befrom 5 mm to 20 mm, such as 10 to 15 mm.

In this ninth additional example, any of the ablation elements maycomprise one or more of an RF ablation electrode, a coiled wireelectrode, a laser cut RF electrode, a RF electrode printed withconductive ink, a RF electrode on an expandable balloon (e.g.,conductive ink, flexible circuits,), a conductive membrane RF electrode,a RF electrodes on an expandable cage or mesh, an ultrasound ablationtransducer, an electroporation electrodes, an cryoablation element, or avirtual RF electrode.

In this ninth additional example, the ablation element may be adapted todeliver ablation energy circumferentially (radially symmetric around theablation element/around the vessel).

In this ninth additional example, the catheter may further include aproximal radiopaque marker positioned on the shaft at or proximal to aproximal end of the ablation element.

In this ninth additional example, the catheter may further a distalradiopaque marker positioned on the shaft distal to a distal end of theablation element(s).

In this ninth additional example, the catheter may include an axialspace between a distal radiopaque marker and a distal end of theablation element.

Any of the methods in any of the additional methods may be used with anyof catheters in the additional examples. Any of the catheters in theadditional examples may be used with methods herein or used in ways thatare not described herein.

What is claimed is:
 1. A system for ablating a greater splanchnic nervefrom within an intercostal vein, the system comprising: an ablationcatheter, including: an elongate shaft having a length such that atleast a portion of a linear distal section of the elongate shaft can bepositioned in a T9, T10, or T11 intercostal vein, distal and proximalelectrically conductive flexible and coiled ablation electrodes carriedby the linear distal section, the distal and proximal electricallyconductive flexible and coiled ablation electrodes together having anaxial length from 5 mm-25 mm and an axial spacing therebetween that isnot more than 2.0 mm, a plurality of distal electrode irrigation portsin a helical configuration disposed between windings in at least acentral section of the distal electrode, a plurality of proximalelectrode irrigation ports in a helical configuration disposed betweenwindings in at least a central section of the proximal electrode, aplurality of distal irrigation ports distal to the distal electrode, theplurality of distal irrigation ports axially aligned and equidistantlyspaced circumferentially around the linear distal section, a pluralityof central irrigation ports axially between the distal electrode andproximal electrode, the plurality of central irrigation ports axiallyaligned and equidistantly spaced circumferentially around the lineardistal section; and an external device or system adapted to be coupledto the ablation catheter so as to create operable communication with theablation catheter, the external deice or system including: a poweroutput module adapted to deliver a first waveform of ablative RF energywith an initial power from 15-50 W and a second waveform of ablative RFenergy with an initial power from 15-50 W, and a module adapted toreceive information indicative of at least one of a sensed temperatureor measured impedance and determine if at least one of the sensedtemperature or the measured impedance is at or above a limit, and if atleast one of the sensed temperature or the measured impedance is at orabove a threshold limit, cause the power output module to decrease thepower of at least one of the first waveform and the second waveform. 2.The system of claim 1, wherein the module comprises at least one of atemperature limit module or an impedance limit module.
 3. The system ofclaim 1, wherein if at least one of the sensed temperature or themeasured impedance is at or above a threshold limit, and a minimumtherapy time has not yet passed, the module is adapted to cause thepower output module to reduce the power of at least one of the firstwaveform and second waveform to a secondary power less than the initialpower.
 4. The system of claim 3, wherein the secondary power is from5-10 W less than the initial power.
 5. The system of claim 1, wherein ifat least one of the sensed temperature or the measured impedance is ator above a threshold limit, and a minimum therapy time has passed, themodule is adapted to cause the power output module to reduce the powerof at least one of the first waveform and second waveform to a secondarypower from 0 W to 1 W.
 6. The system of claim 1, wherein the poweroutput module is adapted to deliver asynchronous first and secondwaveforms.
 7. The system of claim 1, wherein the power output module isadapted to deliver the first waveform of ablative RF energy with aninitial power of 25 W and the second waveform of ablative RF energy withan initial power of 25 W.
 8. The system of claim 1, wherein the moduleis adapted to determine if the sensed temperature is at or above 40° C.to 95° C., optionally at or above 90° C.
 9. The system of claim 1,wherein the module is adapted to determine if the measured impedance isat or above 200 to 500 ohms, optionally at or above 500 ohms.
 10. Thesystem of claim 1, wherein the power output module is adapted with adefault system to deliver the ablative energy from 30 seconds to 180seconds.